What's new? The whole car has been a PR stunt from the word go.

I shudder to imagine the resources wasted when do-gooders junked their old cars to "upgrade" to it, to find it's barely if any more economical than its conventional competitors.

Running the airco might be a tad optimistic, but then in the UK it would hardly be necessary anyway. it might get up enough steam to power a digital clock.

"However, the Prius remains the only car being driven globally which is actually different from normal internal combustion jobs in its power-train engineering."

Oh, really?

Never heard of the Lexus GS 450h?

Or the Honda Civic Hybrid?

Lexus RX 400h?

Lexus LS 600h?

And those are just mainstream cars...

Incidentally, all of those are 'normal' looking, well equipped cars, unlike the 'hair shirt and sandals' Prius.

And the Lexuses (Lexi?) are SERIOUSLY quick - 0-62 in 3.5 sec from a spacious luxury 4 door saloon anyone?

Facts right please -

"...the Prius remains the only car being driven globally which is actually different from normal internal combustion jobs in its power-train engineering..."

I know Toyota make Lexus, but the P(r)i(o)us isn't the only hybrid powertrain, and I think Lexus is pretty much a worldwide brand.

In counties where there's more sun than we get in dear old blighty it might be useful to recharge batteries while the car is parked... But we'd need to see figures for the rating of the panel etc. etc.

Say a 1m square panel catching sun 8 hours/day (for a sunny place like California, parked outside during a working day). With a 10% efficient panel, that's about 0.8 kw/h, or 2.8 MJ.

30 Litres of gasoline is about 1GJ. So 2.8MJ is 0.084 litres of gas per day. If the daily commute uses two litres (~20 miles), that's a 4.2% improvement in fuel consumption.

To decide if it makes economic sense one has to know what the solar panel option costs. To decide if it makes "green" sense, what the CO2 cost of making the panel is, compared to the fuel saved over the life of the car.

In the UK, halve the saving. The UK is probably the worst place in the developed world for deploying solar power. Most of the world is sunnier!

Im sorry, but that can't be right.

I'm not aware of an Lexus that can do 0-62 in 3.5 seconds?! Which one do you think can, as I'm quietly confident you're wrong. ;-)

Finally, a car that meets the advertised dream of driving in to the sunset.

"Can't come home, low on petrol, have to follow the sun".

Erm, wouldn't chucking the solar stuff on top (not forgetting the control gear) add to the overall weight of the car? How often would the panels need changing as they would go opaque quickly due to abrasion or will they be faced with glass? Why do they keep insisting on petrol? Why is it mainly tossers who buy the things?

I am not going to waste my hard earned cash on these Solar versions...

I'll wait for the tried and tested Hydo Electric version with your own reservoir in the boot which will use gravity to drop the water down through turbines under the back seats into the foot well (passengers might need wellies) then at night when electricity is cheap pump it back into your boot. Most probably just as efficient as the solar version in blighty.

Concept tested by Toyota North Wales in the '80s:

http://en.wikipedia.org/wiki/Dinorwig_Power_Station

.... which allows you to easily spot those whom in earlier times would have been sporting hair shirts. Even GM's EV1 was a better looking vehicle, and a more environmentally-friendly one. I can easily argue that a kit car built from secondhand parts is more ecologically sound solution than the Prius, and a whole lot more fun! For those who want their hair shirt in scintilating colour, there is even a gent in Essex with a Westfield with a Mondeo diesel engine (heresy!) modified to run on corn oil. No solar panels required, thank you, air-conditioning and a smile are built-in!

Solar cells really do produce very little when compared to the output of an internal combustion engine, and the electrical requirements of a car. One headlamp is 55 watts, just go and look at the size of the panel you need to run that. (Yes I know, who wants a solar powered headlight!).

If you really want to be green and have amazing economy, you could beat the prius just by getting a small diesel from the 1990s!

Sure it won't have an aircon button to suck 10% of the engine power, but it does have these glass thing you can open, called windows. (No they're not just an operating system).

If you really want to go to town, chuck 50% old veggi oil in with the diesel, and tada, you've just halved your usage of fossil fuel.

We really haven't progressed much.

It might not do too much, but it's nice to see steps in the right direction. They will want add a bit of pressure for the panel to be as light as possible - and moves towards making solar panels lighter will mean that a few years later some advanced cars may start sporting bigger panel areas on the roof, bonnet and maybe even the doors.

Once that sort of area is covered, then people who only make a few short journeys each week will see their fuel costs cut by a percentage worth looking at.

For the people that make longer journeys - well perhaps we'll see some solar power recharge spots with some early adopter companies putting up a PV array to charge up their employees electric cars. Woking already has a free recharge spot in one of the car parks for electric cars to get a free refill, and since Woking also has a big photovoltaic facade by the train station you could almost say people are getting their free solar power recharge there.

they intend to handle end-of-life for all those highly toxic solar cells?

Maybe they'll just crush e'm, and ship the cubes to India/China!

The solar panel on the Prius is pure gimmick!

I spoke to the Honda salesman about the Civic hybrid. I was expecting to be able to drive for some distance on battery (only kicking in the petrol engine when it needed to (for charging etc) or when you'd gone over a certain speed. The Honda Hybrid seemed to just switch the engine off when it was idle (like the BMW/Mini Engines with Efficient Dynamics). He said for the most part - I'd be on petrol... It is apparently a power assist hybrid.

http://en.wikipedia.org/wiki/Hybrid_Vehicle_Drivetrains#Power_assist_hybrid

I'm more interested in the biodiesels and cars than run on waste vegtable oil (chip fat).

The Honda salesman did interest me in the FCX concept (Fuel Cell) and said that would be in production next year (apparently). They biggest issue is apparently getting UK petrol stations to stock hydrogen.

Given Tokyo's summer weather, why not add hydroelectric assist as well...

... when your battery starts to go it'll likely still have enough charge to get you started because of the solar panel topping it up as quickly as it drains.

I have driven three cars, two needed battery top-ups after being stood still for a long time. Solar panels from Maplin prevented this.

In this part of the world (HK), the extra pollution caused by vehicles running their engines to keep air-conditioning going is a significant issue, and one that's currently being debated hotly (sorry about the pun). The government is considering forcing car drivers to turn off their engines when parked, and understandably this makes a lot of mini-bus and taxi drivers upset.

So I'd be interested to know how big and/or more efficient a solar panel would have to be to keep the air-conditioning going for, say 15-20 minutes (which would cover most stop-periods I think).

I think you'll find the actual productivity of the battery part on the 400h and 600h is extremely low. It's almost laughable. And have you seen the weight of those monsters? They should harness the power of their own gravity instead.

If they could actually power the car for 80% of the time under 30mph, they'd make sense to me. At the moment it's pure gimmick.

If it provides enough power to run the aircon when the car is parked in the sun with the engine off and the windows closed, that could be worthwhile. IIRC Saab had a concept car that did that years ago.

... does it take to produce the solar panel, compared to how much it will produce over the lifetime of the car?

Jeff

I can see the logic of using solar energy to power air-con (when it's sunny, you need air-con) but surely there are better ways of harvesting solar power for the purpose of providing cooling?

I drove one for a week - a hire car - and it was very economical actually. It's good in town because the engine switches itself off and doesn't come on uness you do about 10mph+. You can't drive much faster than that with the battery alone. I guess for Central London it would be an ideal vehicle! The brakes charge up the battery which is a good use of otherwise wasted energy.

I wouldn't own one though, because it feels rather heavy to drive, no doubt because of the dead weight of those batteries! I would imaging the maintenance costs would be quite high too.

I'd rather buy a diesel instead, for fuel economy's sake.

To be fair, as far as I can tell modern air-co units take less than 10%. It's also worth remembering that you can lose 10% in fual eceonomy while driving with the windows down.

You also mention using veg oil etc. Apparantly you need to be careful as this can eat the seals in some cars, plus there's the issue of HM Revenue.........

Finaly, according to Ford diesel cars are not as efficient for short journeys. I've certainly seen that for myself. Compared to a peterol car the diesel takes an age to get up to temperature and hates short journeys.

The roof is big enough for a 50 to 100 watt panel, which could produce quite a bit of power over time. My five watt panel will completely recharge a deep cycle marine battery in about five days. You have to remember that though solar panels produce a miniscule amount of power, if coupled with batteries, it adds up.

Toyota are missing a trick here. Instead of photovoltiac cells, they should use solar-thermal cells. They can provide much higher energy transformation ratios than photo cells. Use an efficient heat pump and you should be able to generate steam. Either use that to run a steam turbine generator to recharge the battery, or directly to power the car.

Burn your biodiesel/biomass to supplement the sun's heat for your external combustion steam engine and Robert's your mother's brother. In times of shortage you can use anything inflammable, white-spirit, meths, coal, White Lightning...

Mines the anorak with the Stanley Steamer lapel badge, and the Ian Allen trainspotter's guide in the pocket.

Is Toyota now taking design ideas from my 2006 Skoda? My Skoda Superb has a solar panel in the sun roof which runs the blower when I park in the sun. This prevents the impression of “getting into the oven” after the car has been parked in the sun for any time. It saves the air con working flat out to return the interior to something like a liveable temperature.

0-62 in "less than 6 seconds" according to Lexus. Of course, to quote St Jeremy of Clarkson: "Hybrid? Yeah, in the same way that my Ford GT would be a hybrid if I put a child’s windmill on the roof."

It's a great idea. A big market for the Prius is So Cal (partly due to local pre-EV regulations), where temperature rise when parked is a serious ergonomic problem. This solar panel might do little for driving the car, but if it means the car can keep itself circulating air (and thus cooler) when parked without flattening the traction battery, then that's worth it on its own. Such cooling is well-established on boats, and AFAIR Saab did it a while back too.

As to overall efficiency, then the Prius is a brilliant way to make an urban taxi. It's _not_ a super-efficient motorway cruiser (and not claimed to be one), but i's a damned clever hybrid.

"Toyota has thus far turned its face resolutely away from cars which can store enough electricity to make journeys solely on battery power"

Slightly unfair - the next model of the Prius will be a plugin, and they have already been road testing the development versions:

http://blogs.cars.com/kickingtires/2008/01/prius-plug-in.html

Might be interesting getting one then....

These solar panels will be fixed - they cannot be angled to be perpendicular to the sun (unless you want to add a heck of a lot more drag), so you can forget the additional 2.8MJ (as per Nigel's comment above), you'll barely get half of that.

Then there are shadows from trees and buildings (as well as from our obligatory clouds).

Then there's the additional weight and drag of the panels (probably not so significant but they add up).

All these factors together make me wonder if it is really worth it.

Then there's the fact they are 90% inefficient, that being turned into heat - put one of those on your roof and you'll need more power than the panel will provide to run the air con just to keep the car cool !!!

That's really quite simple - find out the cost of the panel, and then divide by the cheapest available energy.

Lets assume for a moment that it costs £100 - much less than the cost of a barrel of oil at the moment - therefore the CO2 emissions must be substantially lower than that.

It amazes me how many people think that there might be tons and tons of Carbon used to make a £1 product!

Jeremy Clarkson was talking bollocks (again) - The hybrid parts add 147KW to the maximum output of 250KW. Although the batteries would not allow this to be sustained for extended periods.

The "solar panel for the Prius" idea has already been done by some companies in the USA.

I love the fact that a Mini (with an engine designed in the 50s) with £150 of mods is just as economical as a Prius and has a better power to weight ratio.

Cooking oil and HM revenue...

According to HMRC.gov.uk you can use 2500 litres for your own consumption in one tax year before you need to declare or pay duty.

http://www.hmrc.gov.uk/si/2007-1640-em.pdf (pdf warning)

You do have to be careful, but not 'cause of seals, but because the viscocity of veg oil (google 'SVO in diesels' ) when cold and the glycerine in it. Older low pressure diesels cope ok with 75%/25% mixes, common rail ones don't! In fact their pumps fail spectacularly with the extra load of thicker oil

Following on from the “it would be nice to run the aircon” theme, why not use a solar powered system to run a cooling system directly, in the same way that a gas-powered fridge works. No heat to electricity to chemical to electricity to motion transducers required, just heat to motion (of the refrigerant).

http://home.howstuffworks.com/refrigerator5.htm

It would only be good as a backup system; no good for de-misting on a rainy day etc.

Just an idea, feel free to build on it or shoot it down.

1) Clarkson-san did a production "costing" on the Prius on the 1st edition of the new Top Gear series (air date 29th June I think) where he advised people about the cost of shipping Nickel (I think it was) from South America to Europe to be turned into batteries, which are then shipped to Japan....very "eco-friendly" in his opinion...!

But then again:

2) Surely any extra "free" energy (such as solar) that can be stored within the car (such as the battery) surely is a GOOD thing....such that over the lifetime of the vehicle, it uses less energy because of the "trickle" from the panels (and not withstanding the production and environmental cost of solar panels in the first place).

Maybe, if more vehicles, such as those with large flat tops, such as London's bendy buses or 40 ft trailers each had solar panels, then overall, all this extra energy could help....?

IT Angle - is there one? (OK - so "solar panels power new generation of in-car GPS" might be one - doh !! )

"five watt panel will completely recharge a deep cycle marine battery in about five days"

Hmmmm

Say battery is 100Ah @ 12V charged by 5W 12V panel

Solar panel will produce maximum 5/12= 0.4A

Time to recharge at max is 100/0.4 = 250 hours

.......or about 10 days assuming bright sunlight 24 hours per day

Bovine extract anyone?

Tanfield have the second most popular eletric motor design. Which is being used by Sainsburys M&S and TNT in the UK. Globally lots of companies use them.

They orginally made eletric milk floats back in the 70's 80's they butt of many a joke, but now they are making Long haul Artic lorries and eletric vans for Ford and Scania, but only for large customers.

This is the future for transport haulage..

"fitted onto a car roof (as the Prius ones will reportedly be)" ... that's [onto] not [into] the roof. Has any one bothered to factor in added drag?

The "life of the vehicle" argument makes it [less viable], not [more]. The "life of the solar cell" argument is only very slightly better, presuming you never need the roofrack, the climate improves dramatically and of course assuming you are not involved in anything excessively bumpy or sudden.

However, the Prius is singularly unique in that not only is it inherantly uneconomic in concept, not only is it one of the most environmentally unsound vehicles to construct, not only is it no more efficient than a dirty 20 year old diesel but it is failing to produce on all these levels whilst promoting the destruction of countless perfectly good road vehicles, all in the name of sales. The weak may inherit the Earth, but it is the weakminded who buy into Prius.

"0-62 in less than 6 seconds" as I seem to recall reading above can easily be achieved and is most particularly satisfying to see it done with a Prius... Find a nice cliff, introduce the vehicle to a vertical drop scenario, the further the better. Takes a few seconds to pick up speed then it's down all the way. The most rewarding part has to be the sudden stop at the end.

In the US there is a grass roots effort shaping up where the mentioned Toyota Prius is modified to actually run on electric for extended periods.

For more details see: http://www.spiritofdc.com

@Chris et al. It's the Atkinson cycle engine.

Yes, the Prius is indeed the only production car with that kind of powertrain. None of the other hybrids, hard or soft, have an Atkinson cycle engine. This engine produces more power in a peak, whereas the standard I.C. engine produces power in a wide band. I believe it's something to do with having a longer rest at the top of the first stroke, which allows the explosion to push the cylinder head down right at the beginning of the stroke. Because the power isn't produced in such a "shock", the engine doesn't have to be so armoured, therefore it can be more compact, therefore lighter. Look it up on Wikipedia, because I don't have time.

Just a thought: it would be hilarious to try running a car that size without electrical assistance on just the Atkinson motor. This is why the Insight, with its standard 1.0 liter engine, was so small.

.. as any fule do know?

Whereas over here in Blighty we've got the Battery Vehicle society who, rather than taking godawful, high-cockometer-rated, clunky designs, and modding them up to very slightly above diesels that are commonly available over here, build electric cars. Doing things properly, y'know?

And not only that, they help each other and talk to each other and foster a community spirit as opposed to scrounging around to pay for someones' roadtrip across America. I mean surely the greenest thing would be to NOT drive across America!?

Even our Kit-Car industry's got in on the act- at Stoneleigh this year on the Mills Extreme Vehicles stand was an MEV R2 fitted with LiFeBatt's LiFePO4 batteries, some control stuff and a NetGain Warp9 motor. 330BHP equivalent, topped out over 100mph, decent accelleration, about £17k (of which 10k was the batteries... you could build it a lot cheaper- though with less range- if you used SLAs) and fantastic accelleration. Only problem was the range of 35 miles- which is still perfectly suitable for driving about town and my commute. And given that a Prius should only be used around town or it's just a heavy, inefficient petrol car, and that they normally carry one person (or it'd overheat from the intense feeling of self satisfaction), it's vastly superior to them. Oh, and no nickel. Lithium, Iron and Phosphates- all, IIRC, available from and sourced from the UK. And they last longer than the Prius.

So to conclude, the UK's doing things properly. You're creating large, heavy vehicles and still cheating by keeping the petrol engine...

flame on.

Y'know, the one who said that a Lexus reaches 0-62 in 3.5″. He didn't specify the speed unit. Although a moderately intelligent reader will automatically assume it's 62 mph (since 62 mph ≈ 100 km/h), I believe that 0-62 km/h is easily achieved in 3.5 sec by a, say, GS450h.

Mine's the one with the conversion tables on its back.

cause he proved a BMW M3 was more environmentally friendly than a prius - top marks that man

For you Prius doubters, are there any other cars manufactured today that get 55 mpg? I sure don't know of any. I get between 50 and 55 mpg every day no matter what speed I average. The only time I ever got less (48 mpg), was traveling through some 12,000 ft mountain passes. The car is very comfortable, with GPS, backup camera, 6 disc cd player, full airbag system, leather, etc. My only criticism is the brakes are a bit touchy. The motor seamlessly kicks in ONLY when needed, and speed has no relevance as some people seem to think. It depends more on the state of the batteries charge and the slope. I have driven many miles, slightly down hill, at highway speeds without the motor ever starting up. If I am driving on even a slight up hill grade, the motor nearly always kicks in. It's no sports car, but I highly recommend this car to everyone. Diesel engines are somewhat efficient, but no where near stoichiometric. My new 2008 Ford F-350 diesel gets 11 mpg. Ouch! So, as far as the added solar panels, if they save one gallon of go juice per day, they probably will be worth their extra cost.

While I agree with you that the whole car has been a metrosexual PR stunt from the beginning, a rooftop solar is something that will benefit any car. Every car loses some of its battery charge when parked (up to 5-8% a day for some combinations of car+ alarm) and it is recovered during the most inefficient engine operating mode (while cold). A solar on the roof will go a long way towards improving that. In addition to that a solar on the roof coupled with an electric driven aircon can go a long way towards keeping the car environment nice and usable on those +30C days in the middle of a hot parking lot (this used to be an option on the S-class Merc by the way). Once again - savings from having to run the aircon fullblast when the engine is cold. And so on. In fact - it is something that is worth having on any car and not just the Prius.

... cooking a catering pot of chilli on a 4-ring stove, then holding a Clipper lighter to it?

"To be fair, as far as I can tell modern air-co units take less than 10%."

That was a finger in the air figure, kind of aimed at the Prius, which doesn't have many geegees under the bonnet to start with!

"It's also worth remembering that you can lose 10% in fuel economy while driving with the windows down."

A valid point, although I think you'd need all the windows open to get near 10%, same goes for roof racks.

"You also mention using veg oil etc. Apparently you need to be careful as this can eat the seals in some cars, plus there's the issue of HM Revenue........."

I don't think it eats the seals so much as shifts all the old gunk that has collected there, which has probably been preventing a leak in the first place.

No tax issue with HM Gov any more, personal use, less than 2500 litre (I think) and it doesn't cost you a penny.

"Finally, according to Ford diesel cars are not as efficient for short journeys. I've certainly seen that for myself. Compared to a petrol car the diesel takes an age to get up to temperature and hates short journeys."

Indeed, but for short journeys a bus, your legs or a bicycle would be even better.

This means that we are actually on the same page as I am a member of the Electric Vehicle Association of Greater Washington DC. Here is the link: http://www.evadc.org/

I am currently working out the details to convert my 1997 VW Passat GLX VR6 to an all electric.

Also I see hybrids as an evolutionary step toward all electric vehicles. Not as an end to itself.

As for the Pluggable I participated in the ride along and although we were carrying 3 large humans and other gear we still averaged 69 miles to the gallon and made our journey of 220 miles using only 3.5 gal (13.25 liters).

Sidebar yes most people in the US commute alone, don't single out the Prius drivers.

Flame off

sorry but i have my doubts (even though i used to own a VW polo that consistantly got 45+ mpg)

you might wanna watch this http://www.youtube.com/watch?v=PP6fe6i1vaY

It's Maplin (singular) - always has been.

No doubt the author also plays with Legos?

-- Paris - because she's been buying batteries for her..er..appliances..from Maplin ever since she bankrupted the Tandy battery club.

Some of the Prius-knockers out there should learn to compare like with like. A Prius is a family-sized car. Comparing it to a Mini or Polo is comparing one peach to one apricot. I'm not aware of any similar-sized car that can get nearly such good economy around town. I do hope Toyota do a hybrid Yaris next and would expect it to beat all non-hybrid small hatchbacks in city traffic by 10-20%.

The battery is not there to power the car for long. It's there to store energy when the car slows down, instead of wasting it as heat in the brake disks. The electric motor assists the petrol motor for brief bursts of acceleration and for uphill. For cruising, it's all-petrol, using an Atkinson engine that's more efficient than a standard car engine, but which is insufficiently flexible to be used in a standard un-assisted car.

If your everyday motoring is not in stop-start traffic, the advantages of a Prius are lessened, because there is less braking to be regenerated. Rural motorists might do better with a non-hybrid, though electrical assist still gives a nice combination of efficiency and decently zippy performance.

In case you think I'm biassed by owning one, I'm not. I don't need to carry a family and I mostly drive on motorways at week-ends. For me, a smaller diesel hatchback is more efficient.

There's no point Toyota building an all-battery car until big fast-charge batteries exist and a nationwide fast-charge service-station infrastructure is in place. It may come (for batteries read Ultracapacitors). Until then, not turning forward momentum into waste heat every time the car stops or slows is a good idea, which the Prius has solved. Frankly, if we accepted the argument that a small improvement was too small to be worth making, we'd still be driving model-T Fords (if we'd ever bothered to invent the car in the first place, that is!)

Flame off indeed! Thanks for the heads up on the washington group, I'll check them out later...

@Waves

There are tonnes of cars out there that will beat 45mpg. Even an old XJ40 soveign Jaguar will (for a short period of time with careful driving). A lot of them will manage a consistent 45mpg. Very few in the 'States due to a lack of consumer demand. You just wait until your oil starts to noticeably dry up and petrol starts getting towards the £1.60 per litre (about $10 a gallon if my cigarette packet is accurate) we've got over here- you'll see a huge increase in European and Japanese cars on the roads of the 'states while the American corps try to figure out how to sell cars that no-one can afford to run. For example, the Ford pickup you mentioned would be... a little... uneconomical to run. As in almost a dollar per mile.

Aren't American cars really good for torque rather than power/speed/handling? Wouldn't this high-torque-starting behaviour map onto series-would 'leccy motors quite nicely?

...Using the same technology as locomotives have been since steam went away? Diesel-electric or gasoline-electric. Internal combustion engines designed to put out peak power at peak efficiency, driving a generator that drives strong electric motors. Throw just a few batteries in the electrical side of the system for the initial draw electric motors like at 0rpm. No need for heavy banks.

but here in the UK you'll need to spend a serious amount of money to get any return from it, plus the price of panels are still HIDEOUSLY expensive compared to the US etc. Sure you could make your own panels by buying a large batch of cells & wiring them up yourself into waterproof frames, but it's still not cheap and a lot of hassle.

One minor flaw in having solar-roof cars, I haven't seen many garages with see-through roofs...

I believe the original Honda car (1200 cc 2cyl., curb weight about 1000 lbs) got over 50 mpg. My family had one in the mid-70s. It was so small and light, the neighborhood kids used to pick it up and turn it sideways in our parking space as a prank. The next model year it was replaced by the more conventionally-sized Civic.

Running a few vehicles on used vegetable oil (aka biodiesel) is probably feasible, but total conversion to several million? There aren't enough deep fat fryers in the entire world to provide enough veg oil for the cars in one large city (say London) much less the entire UK, or the US, for sure. Enough corn is already being diverted to ethanol production that it is having an effect on food prices. I suppose some of that could also have oil extracted from it, but it isn't sustainable agriculturally.

James, Prius bashers, and others with doubts about the Prius' gas mileage. I do not blame you for having these doubts. I actually expected people on this post, to not believe the 50 to 55 mpg (US gallon) that I get. Thats OK, I don't really care if anyone believes this or not. I'm not really attempting to convince, or sway anyone. I know what mpg my Prius gets, and thats what counts when I pull up to the pump. I am truly not stretching those figures. Those are hard numbers that don't seem to vary much. The sticker on the Prius claimed 60 mpg average. I figured if I got 40 to 45 mpg, I would still be happy, so I bought the car. I have never averaged on a long drive, more than 57 mpg, but I would have to say, 52 mpg is what I get mostly. I was an engineer for a transportation company and I drove 60 miles each way to work. My speed averaged about 70 mph and I averaged 52 mpg on a regular basis. Believe it or not. I just thought some of you would like to know. By the way, I'm not driving a Prius to save the world. I'm driving it because its very comfortable inside with lots of room and creature comforts, and it gets 52 mpg. For any of you self righteous "save the world" types, Prius batteries will never occupy more space in land fills than old computers like the one you are typing on right now! So you may want to step down from your high horse, because you aren't fooling anyone.

Additionally,many years ago, I purchased new, a 1972 Honda 600 coupe for $1,750 USD. It was bright orange! It also got 55 mpg, but even though it was a four seater, it was sort of like a motorcycle with a body. It was tiny inside and out, noisy at highway speeds, had no creature comforts except a radio, and had no safety devices except seat belts. It may have gotten great gas mileage, but it was certainly no Prius!

P.S. James, I will check out the web site you have listed, but no matter what they have to say, it will not change the fact that I average 50 to 55 mpg, in relative safety and in comfort.

P.S.2 The prius has no roof rack and the roof is actually aerodynamically designed to minimize the drag coefficient.

but then this is just a PR gimmick since PV tech is no were near where it has to be for a Prius mounted PV panel to do much but cost more than it saves.

Using a fan to keep the inside air temp down to the level of the outside air temp with would save more than that PV panel is going to save running the AC. Keeping the inside temp down so that AC doesn't have so much heat to remove initially also makes it more comfortable for the occupants too.

This PV panel thing will backfire on Toyota since it's obviously a gimmick and just adds to the cost of the vehicle. I hope this idea doesn't see daylight.

Actually Ford also use an Atkinson Cycle engine in their hybrids.

The nickel in NiMH batteries is recyclable. The manufacturers have placed bounties on the battery packs to ensure they don't enter the waste stream. This should help offset future consumption of raw ore.

Our 2002 Prius (old model) consistently gets 45mpg or better in mixed city/highway driving. Our 2005 Ford Escape gets nearly 30mpg in the same (quite good for a 4wd that can tow a small trailer).

By the way, maintenance on hybrid vehicles is often LESS than on similar conventional cars. The Toyota and Ford systems do not employ a traditional transmission. Modern automatic transmissions are often considered non-servicable and replacement can run into the thousands.

Sort of an important point, surely? I've a couple of Maplin ones in my car that probably amount to about a square foot of panel all told. They produce 3W - hardly a huge amount. It's going to need to be a dirty great panel to do anything significant for this car.

"are there any other cars manufactured today that get 55 mpg?"

Yes, lots. For example the Fiat Panda 1.3 16v Multijet gets 65.7mpg for the diesel, and 76.3mpg for the petrol. OK so it might not be the most exciting car in the world, but at least, unlike the Prius, people don't shout and throw things at you when you drive past.

55mpg, for a smaller-mid size European car is pretty average really. There are plenty on (non-hybrid) cars available with much better mpg. Annoyingly, I can't remember which one it is, but one of the "super minis" gets over 100 (if you're really careful)

I'm still amazed that anyone thinks that by whacking a massive great heavy motor, and an enormous heavy battery in a relativly small car, along with it's norml hulking engine, it gets them magically better performance. All the Prius does is run it's batteries down around town, then the second you get out into the country, the engine has to run twice as hard to charge the batteries back up again. All you do is save your pollution for the countryside. Thanks a lot. You kill baby foxes with your stupid Priuses, choking them to death on your sickening fumes. Jerks.

And if you charge it off the grid, it's even worse. If everyone in the country got a hybrid and charged it up at home, every day at about half past five the entire national grid would fail, not to mention the fact that most of the energy is generated from oil and coal fired power stations.

This new solar panel seems like more of the same. Indulgant crap to keep people who can't be bothered to actually do anything about helping the environment themselves feeling smug about "saving the planet". There's no way in hell a solar panel is going to be worth the extra weight of dragging it around, nor the energy or pollution to make it, for it's pathetic trickle of energy. You don't get solar panels for the environment, you get them so you get cheaper power. They're bad for the environment, and so are huge motors and batteries. All it means is cheaper petrol for you, you cheapskates.

A solar panel to generate the energy for your aircon? If you want to "save the planet" so badly, get a car WITHOUT AIRCON. Better still, walk. It might give you some exercise other than the endless flapping of your jaws about how you "want to be part of the solution, not part of the problem". You'll never be Captian Planet, get over it. Idiots.

James, I watched several You Tube features by the same Prius basher. I have never viewed such nonsense and one sided commentaries in my life. The Prius may not be as nice, or as fast as the BMW, but to get the gas mileage that this Prius basher said he got with the comparative test was certainly a joke. I could get better gas mileage with my parking brake set. I get 52 mpg every day. END OF STORY. Anyone watching this crack pot can see he has some sort of vendetta, or agenda against the Prius. Again, I don't really care what this guy or any other doubting Thomas thinks. It's getting 52 mpg that matters to me. You can all have doubts, laugh out loud, falsely compare cars, and dream of a car that gets this kind of mileage, but until engineers figure out how to crack the Hydrogen fuel cell problems ( and unfortunately, there are several), the Prius gets better gas mileage than ANY other current production car. The Prius has as much power and acceleration as most economy cars out there.The highest speed limit here in the US is now 75 mph, and the Prius does this and more with no problem. If I want to go faster legally (I got a speeding ticket going 82 mph in the Prius) , it will have to be on a race track. If that is the case, I won't be concerned with fuel economy!

Running a solar company, I would suggest using flexible A-si panels. They can get 10% plus efficiency, and are much better in diffuse (cloudy) weather. Current costing is about $10 a watt, but:

they are super light weight- think a few grams per watt.

b) super flexible, and super thin, (2mm maybe?) so can be moulded to the top of the car and not look like a 70s roofrack with the drag issues. IMO, could probably get 50-80W worth of panels on the roof/bonnet of a prius... which would be a fair bit of extra energy to run the air-con and similar. Possibly even trickle-charge the main battery?

BMW 520dSE 0-62mph 8.3s Top Speed 144mph Consumption 55.4mpg

Toyota Prius 0-60 10.9s Top Speed 106mph

Puuuhlease, "are there any other cars manufactured today that get 55 mpg?". In Europe we make diesel engines smaller than the "little" 17 bazillion litre jobbies you use that get you from BestBuy to the McDonalds parking lot next door on only 8 hogsheads of diesel. I can get 60mpg out of a 1.9 litre diesel Saab without driving like a pensioner. The worst of the VW Bluemotion offerings will get 55mpg easy...

So, with one of these cars, if I *was* somewhere sunny enough to make solar power worthwhile, should I park it in the sun to help power the aircon, or just park it in the shade so it didn't heat up as much in the first place?

I ride to job sites in a Prius a lot and it's pretty incredible. We often get close to 50 MPG in it, but we drive it very easy. If you drive it like a sports car the mileage goes to hell real fast, but if you treat it like it's designed to be driven, it really does provide exceptional mileage.

In my eyes, the real value of the Toyota Prius is that it got the alternative drivetrain out of the concept cars and into the mass market. Suddenly all the car manufacturers had to come up with a similar or (,and here is the good part,) better product.

In my eyes, the biggest problem with most hybrid cars available right now, is that one cannot drive the first 100 km or so (to work thus) on batteries only. However, doing so would require the utilization of some really good batteries (like these http://lange-aviation.com/htm/english/products/antares_20e/battery_system.html ), and they again require a slightly more serious investment than most people are ready to make.

The good news is that prices are falling, and that the technology is moving forward.

Personally I hope that my next car can have a primarily electric drivetrain.

....A helicopter because anything is simpler than a vehicle consisting of 10.000 parts doing their best to shake apart.

There's a practical problem affecting the use of solar trickle chargers on most cars - the alarm.

When armed, most (if not all) alarms monitor battery voltage. That's because opening any door will switch on a courtesy light, causing a small drop in battery voltage which is detected and triggers an alarm.

That same drop is detected if your solar trickle charger is in bright sunlight when a cloud passes. The shadow causes a volt drop which is seen as an entry attempt.

Volumetric alarms are probably immune to this phenomenon, but even they usually have a secondary volt-drop detection capability.

> My new 2008 Ford F-350 diesel gets 11 mpg. Ouch!

Unhook the trailer, release the parking brake, or perhaps lighten your foot a bit. My 2000 F-250 diesel got 19.4 mpg at my last fill up. Or have they gone that far downhill in the past 8 years?

The Prius also has a type of CVT (Continuously Variable Transmission) gearbox, meaning that it effectively has an infinite number of gear ratios, and can therefore keep the engine running at optimum RPM's (for fuel economy etc) regardless of how fast the wheels are going round.

If the CVT is smooth enough in moving the car from a standstill I don't see any reason why it would need a secondary source at all.

In fact, we can pick lots of holes in the Prius et al.'s green credentials once manufacturing costs (to environment) etc etc have been taken under consideration, but many forget the following important facts:

A lot of these technologies are new to mass-produced cars and have great potential. Now these are becoming popular - And don't underestimate the importance of Prius et al in helping this to happen - I hope we can expect to see such tech refined, costs reduced and put into more cars.. like CVT, electric motor assist, etc. etc.

Stop slagging this tech off. Unless you want a car-less future very soon, you should be supporting things like this - remember, car's like the Prius are part of the journey to a more sustainable system, not the destination.

Even if some ideas, like bolting solar panels on, seem a bit daft, people need to think of them and people need to try.

Mines the solar powered one...

I greatly enjoyed driving a small diesel while on vacation in the UK recently, but they are still too dirty for California - though strangely enough the big pickups and SUVs can run diesel engines because they're legally "trucks". The car got over 60mpg, though that was probably IMPERIAL gallons, not US gallons - be careful of units! Also, that was the car's own opinion of itself.

So, in California we're stuck with the Prius as the best current alternative, besides bicycles and feet.

OK, if the solar-powered racers can do better than 60mph in the race across Australia, there is interesting energy (and technology) here! In California almost all cars sit outside in the sun 360 days a year. No one uses garages here, either at home or at work. That sunshine is turning into heat anyway, either on the pavement, the roof paint, or heating the car. Using even 10% of it is a win. And there is a lot of interesting new solar technology coming on line - flexible panels, more efficient panels, and cheaper (less efficient) panels.

interesting fact about the Prius is that it has TWO batteries - one for starting the engine and normal automotive-electrical stuff, and the big battery pack for the hybrid stuff. I had to jump-start a friend's Prius after a party then the little battery was dead (lights left on?), while there was plenty of charge in the hybrid pack, which was somehow inaccessible. Here's an IT angle - the control software hasn't been debugged into all the corner cases yet!

Happy trails...

Actually the 12v battery only runs the computers and the like. The engine is actually started by the HV battery...but the 12v battery needs to be able to close the relay on the HV battery for that to happen.

hmmm it takes the ford GT 700hp to do that

http://www.egmcartech.com/2007/10/12/tuner-cars-701hp-ford-gt-by-geigercars-0-62-in-35-sec/

Anyone on here actually realise that almost everyone is comparing the US mpg with their own UK mpg? That makes the Prius seems much worse than a crappy diesel. It gets 66 mpg in UK terms, due to the US having such piddling pints. You won't find an equivalent sized petrol car that gets that good. Comparing diesels to petrols just confuses the issue, you might as well compare them to hydrogen powered cars ("OMG 95mpg!").

Priuses (is that the plural?) are pretty expensive though, and I worked out it would take me 5 years before it actually saved me money over a similar non-hybrid car, although that is without factoring in depreciation (which is pretty low for a Prius). I'll stick with my 45 mpg (UK) old Corolla, which still gets better mileage than most new cars.

If you're going to put a solar panel on the car you should do it right, and have it on an arm so it can angle itself to the sun when parked - folding up when on the move to reduce drag.

Minor observations here:

1) Comparing the mpg of a car built in the 50s (60s, 70s, 80s, etc.) vs. a vehicle manufactured today is stupid. (SEE: Pollution/emission requirements are stricter today and anti-pollution gear creates back-pressure, which decreases mpg. Perhaps, connecting a hose to the tail-pipe of your 50s Mini or original Honda or <stick name of old freaking car with no emission tech here> and inserting it into a closed space might make this clearer for you).

2) Regardless of the energy conversion efficiency of a solar unit, Any comparison of the relative value of a solar power unit of any kind that doesn’t include the cost of purchasing said unit verses the value of the benefit is stupid (SEE: Return on Investment. e.g.: Spending $100 to save 1 penny a day takes 27 years to pay off even if you neglect inflation. Me personally, I’d prefer a better return, especially if the lifespan of the $100 device is around 10 years).

3) Making statements like “get a car WITHOUT AIRCON” when you probably live in a city whose AVERAGE summer high is 75 Deg F / 24 Deg C is pretty egocentric (and in my opinion, stupid). There are people who live in cities with AVERAGE summer highs that exceed 90 Deg F / 32 Deg C. (NOTE 1: For the masses, AVERAGE high temperature is typically significantly less than the PEAK). (NOTE 2: I’m not even factoring in relative humidity). Also, most modern vehicles actually achieve better MPG with windows up and air conditioning running than with windows down and no air conditioning (when moving at highway speeds. The inflection point is generally around 45 mph when the increased drag of open windows begins to exceed the 10% loss from an air conditioner). (SEE: Remove your head from your rectum and put yourself in the place of the person sitting in a car in full sunshine, in a city with an ambient temperature in excess of 100 Deg F, and humidity in excess of 95% - People have been charged with involuntary homicide over leaving their kids in such a situation. ALSO SEE: Quit being stupid, people are going to demand AC).

4) Comparing the mpg of a diesel TRUCK (F-350) verses the mpg of a small passenger SEDAN (Prius) is exceptionally stupid. (SEE: The definitions of engine displacement, torque, horse-power, and actually please just don’t ever, ever, EVER breed).

5) Assuming that someone would hook up an alarm monitor to a battery system and monitor for voltage dips without subtracting incoming voltage is stupid. (SEE: Easily surmountable problem).

6) You eco-chasing Prius vs. Diesel MPG weenies have got nothing on the Aptera -http://www.popularmechanics.com/blogs/automotive_news/4232400.html. (SEE: Over 300 mpg you envious greenie-sheep). (ALSO SEE: “Solar cells mounted under the roof operate an “always-on” climate control system, ensuring the interior never gets too hot or too cold.”). (ALSO, ALSO, SEE: I don’t really give a damn about any of the above issues, I just can’t resist my urges to scream “stupid Stupid STUPID”).

Flames because fire is just good clean fun.

Neil Kay is right - Maplin is the name of the chain of Electronics shops.

Maplins is a fictional holiday camp.

Mine's the yellow blazer with the blue piping.

Park in the open at work, 8 hours of galeforce wind later, I bet you could charge 2 or 3 cars with the wind we got at the moment

Remember the old Ford Merkur? It's the Sierra to the Euro types, like myself.

My old man drove from Bradford to John O Groats in one, and through a mixture of careful slipstreaming and 'gentle high speed' driving [minimal acceleration/breaking, steering on the throttle at speed - the benefits of skinny tyres - cutting empty roundabouts and motorway bends, basically driving to exploit the traffic conditions etc] managed to pull 45mpg out of one tank on the motorway. Economy suffered once he hit the A and B roads beyond Inverness though, as he started caning it and did the last 120-30 miles in two hours flat. Which is pretty impressive if you know what those roads are like...

That's on a 1986, carb fed 1.8 liter Pinto lump giving 0-60 in about nine seconds and topping out about 120-130ish depending on how accurate the speedo is feeling and how much of a headwind you have. So 55Mpg from a Prius really isn't that special, not compared to the selection of EuroBoxes that can pull 45+mpg even when being thrashed into the ground on every trip.

The Prius is an interesting bit of kit, but it's not going to save the world. I personally look forward to a massive jump in electrical storage so that a two hour charge will give me a 400mile range in a medium sized, rear wheel drive and limited slip diff coupe, and also 400lb-ft or torque so that I can leave a set of 11's the length of a football field and take every roundabout with a dab of oppo lock. Or crash, whichever is more likely. Possibly the latter.

Although doing it with a flamespitting straight 6/V8/V12 would be much, much more fun, obviously.

In europe we have had stupendously high [compared to the US] gas prices for years, and the european manufacturers have dealt with it. The reason you are so amazed at the Prius - and we are not - is because, as you rightly state, you have never seen a car pull 40mpg before.

Welcome to the club mate. It's only going to get worse...

Steven R

ok so one guy reckons you can get about 50 to 80 watts of energy with amorphous panels at 10% efficiency. so lets use the better monocrystaline 20% efficient panels and build them into the roof and bonnet to prevent any extra drag. so that'll be 100-160 watts.

lets call that 100 watts for arguments sake. that's 100 joules per second that you'll be able to pump into your battery. Now the efficiency varies depending on the battery technology but i've read that NiMH batteries are about 2/3 efficient so that cuts your energy to 67 joules per second of usable energy. now lets assume that electric motors are about 90% efficient at turning electrical energy into movement so that cuts it down to about 60 joules per second.

So maybe the sunshines and maybe it doesn't. but lets say you get 8hrs of daylight strength at 100 watts. so thats 8x60x60x67 joules per day = about 2 million joules per day to use.

now burning petrol will give you about 35 mega joules per litre. BUT internal combustion engines are notoriously inefficient. an accepted figure is about 20% but this depends on how you drive etc. so that's about 7.5 mega joules per litre of petrol of useful energy.

So, leave your car in the sun for 365 days and earn 2x365 = 730 mega joules. if you use all of this for driving then you'll lose about 10% of this as electric motors are not 100% efficient. so that gives 660 mega joules. divide by 7.5 and it gives you your petrol saved which is 88 litres per year. and at todays prices i guess that's about £100 worth of petrol saving per year.

Please note this is for ANY driver, whether you drive 50 or 50 000 miles per year and that's the beauty about this idea. For most of the time, most of the cars are not being used and mostly cars are left outside in the sun.

There are 24 million cars on the road in the uk. if everyone had these panels fitted that'll be 88x24 = 2.1 BILLION litres of petrol saved PER YEAR. Or considering a tanker takes 50 000 litres then that's 42 240 tankers full. I've read that we buy 47 billion litres of petrol/diesel per year so that's about 5% saving and god knows how many tonnes of CO2.

So there you go, simple maths. It may be wrong in places but i doubt it's out by more than 2 powers either way. so even if that were the case it's still a massive saving.

so all you nay sayers and prius kickers please shut the f£££ up and think of something better before bad mouthing what might be a good idea!

ps. you're welcome to pick any holes you like in the argument, debate is always good and i'm willing to admit i'm wrong (if indeed i am).

pps.The only problem i can see with this is the energy used in producing solar cells which is relatively high. taking somewhere between 1 to 4 years to pay back the energy of making them. Since cars only tend to last about 15 years that's quite a high proportion of their usable life. Solar cells as far as i'm aware do not wear out. lifetimes are quoted at 30 years but i suspect that's just a guess. there is obviously opportunity for recycling them too.

ppps. i suppose an easier way of expressing the amount of energy that could be generated with car solar panels would be 24 million cars x 100 watts = 2 giga watts. or 2 nuclear power stations.

A4 1.9 TDi - full tank lasts 3 1/2 weeks. Commute 40 miles each day. 20 urban, 20 dual carriageway. I don't drive like a pensioner, nor a boy racer. Every 3 1/2 weeks, overall average consumption is 51-52 mpg. Bought it as a 4 year old car for £8K.

To me this is great economy with a low purchase price. As it's a diesel, the engine will run for 200-300,000 miles, so it has a long life. What's the life of a hybrid?

Overall economics make sense to me... but then I like to keep things simple. Look after what you've got!

In 6 or 7 years what happens to the batteries? Into the junkyard?

a while ago, i was watching that american news show that gets broadcasted on bbc news 24 (abc tonight? summat like that), with a human interest story about:

"how a high school dropout has found a way to double the mileage of his car - using off the shelf parts"

intrigued, i continued to watch... basically hed SWAPPED HIS PETROL ENGINE FOR A DIESEL one!!! and this made the f***ing news?!!! He was being hailed as some kind of genius?!!!! unfortunately i was alone at the time so i couldn't rant

(in other news, water = wet, pope = catholic, other daily wail "state of the countries edumacation" headlines (except american not uk)... although to be fair. a good quote from TP said something like: "it isn't the british who think americans are dumb, its *american* editors"),

i merely rolled my eyes. a lot.

paris. because she rolls a lot as well.

1 US gallon = 0.83267384 Imperial gallons

1 Imperial gallon = 1.20095042 US gallons

So approximately

50mpg(us) = 60mpg(uk) = 4.7L/100km

50mpg(uk) = 42mpg(us) = 5.6L/100km

Many years ago one of the Japanese car manufacturers (Mazda I think) sold a luxury saloon with a solar panel in the roof. As well as trickle charging the battery it powered a ventilation fan to keep the car cool when parked in sunny conditions.

Audi currently offer something similar on the A8.

...because until recently we were not allowed small diesels because of problems with the local fuel's sulfur content. The main advantages of owning one are that they're silent and they require virtually no maintainance. Disadvantages are that they are, to all intents and purposes, a golf cart with bucket seats. They also have a 'smug' coefficient (South Park viewers will know what I mean). They also don't get very good fuel mileage in non-commuter traffic.

The hybrid with the mostest is the Honda Insight....you can get up to 70mpg from the thing. There's a reason for this (look it up on the web...)

The EV1 was a practical car and worked very well. It had to be prised from its lessee's fingers --- people used them because they were seriously cheap to run and pretty fast. GM has a sort of death wish - while it was forcibly scrapping EV1s and killing off the original Saturn cars (dirt cheap, reliable as a rock and 35mpg) it was embracing the Hummer (surely one of the most ridiculous product lines to ever grace the planet?).

Um - 52mpg - that's not good, it's OK.

I just did gig up north - a three hour drive in a fully loaded van, with two people up front - we averaged 53mpg.

My 70 miles each way commute I averaged 50mpg over two years.

Both in standard two litre diesels, neither were being driven particularly carefully from a fuel efficiency point of view.

My boss drives a BMW 1 series, but one of the ED range - it regularly gets 70+ mpg on holiday trips, and tends to be pulling 50-60 in town as well.

By the time the pious has been built, and shipped back round the world it's already in significant amounts of carbon debt. Local materials are the key.

The American market doesn't seem to understand what an engine can do, and doesn't care about oil, because they'll just go and invade somewhere else. The EV1 was a good car, and should have been continued. GM should be in serious trouble for ditching it.

To reiterate some points I made earlier which the pro-panel people seem to have missed:

- The sun is never directly overhead, or more correctly, never perpendicular to the panels. This means that a 1msquare panel will not get 1msquare of sunshine. This gets worse the further away from midday it is.

- Clouds and rain (especially in old Blighty but obviously isn't so much of a problem in the US).

- A quick glance outside shows that all cars of carparks in sight get direct sunlight for about 50% of the day - that's buildings for you.

- Then you have to keep the panels clean. Any buildup of dirt will reflect/absorb the light.

So Jimmy, you can divide your result by at least 4. So what will the return of investment of the fancy monocrystaline 20% efficient panels be now? (and it will still get mighty hot in the car, you won’t get anywhere near as much power from the panels to run the aircon to keep the car as cool as having a simple reflective roof – think of a fridge with the door kept open).

Make no mistake, this IS a PR stunt. Don’t get me wrong, I support the usage of elegant and non-particulate emitting solutions which electric based methods can deliver, but we are nowhere near that point; please don’t pretend that we are.

And for the ultimate irony: solar panels are a greenhouse device!

Instead of reflecting the sunlight straight back into space thereby bypassing any CO2 insulation, these simply absorb it and turns the great majority of it directly into heat which is trapped, so killing us all – that is if you subscribe to the notion that ending all human activity will prevent climate change (which high profile ‘green’ companies are implying).

Flame, because it has always been part of the cycle of life.

His reasoning seems as sound as burning a caravan.

For building a "normal" car, you also have to transport the iron ore, the coal, etc-

As for the battery, they will be recycled: it is mandatory in most countries, and in ALL countries that the prius is sold it will be recycled (not only because it is mandatory: it is also composed of valuable materials).

Not only the prius consumes much less, but the fuel that gets burned is burned in a far cleaner way that your "usual" petrol engine.. and that is way more cleanear than a diesel engine.

Would an electric car be better? well, just a little bit, and in that case just make sure that you recycle your batteries...

The solution? Drive less.. what about using your bike? I could conmute to my work using a bike IF I had both a locker and a shower (witch I don't have)...

I had an Audi A4 demonstator about six years ago with elements built into the sunroof - kept the aircon on tickover, so really nothing new.

Wouldn't Toyota (and sister brand Lexus) do better trying to reduce the carbon footprint / air miles that the production of those batteries and drivetrains cause? Isn't this just another eco-con that allows a minority to feel good while making life for others worse? Look at the current arguements re bio-fuel taking vast swathes of arable land away from food production... or "low energy" light bulbs that take more energy to recycle at end of life than they ever save whilst lit.

Not for nothing is this car nicknamed the "Pious"!!

As already mentioned they should be looking at wind powered solutions for us, or even a hybrid where the windmill sails are actually solar panels.

Hybrid cars from Lexus ? They have a letter "H" backside, No?

Prius ! : What else...

Well, as long as you have enough juice to start the engine, no problem.

Oh, sorry, did I disrupt your knee-jerk reaction to any power saving changes.

Sorry. Forget I ever gave a reason why you may want this.

"- Clouds and rain (especially in old Blighty but obviously isn't so much of a problem in the US)."

clouds are transparent at UV ranges. It hardly ever blanks out the majority of sunlight either. We don't get huge deep nimbus clouds for long in the UK.

For reasonable money you can by 60 watt solar cells. With a suitable switchmode charging circuit they will kick 5 amps into a 12 volt battery. Yes you need reasonably bright sunlight to make it happen. I have used one of these with lead acid battery system for months and it will keep a 500mA load runing constantly day and night.

I would think that any car would save fuel if fitted with one of these.

The Prius is a good platform for new automotive technologies. Those electric motors will get better, so will the batterys and you have a car you can use. People will take the electric motors and batterys and build an all electric car, or maybe one with a very small petrol motor.

This business about the parts coming from all over the world, well DUH, don't parts always do that? If I want the best LCD screen I go to Korea, best batteries Belgum? I dunno, they come from where they come from.

I've no idea what you're all pissing and moaning about. Fitting a 50W panel into the roof of a Prius won't do anyone any harm, and will help cool the interior and trickle charge the batteries of the car. And for all those wankers who claim the Prius isn't fuel efficient because some bloke down the pub told them so just have a look at how much fuel it pisses away while it's crawling through a traffic jam, then check out how much energy a Diesel car manages to recover from regen braking, then check out the drag coefficient of the Prius bodyshell, then read a fucking Prius brochure where they carefully explain how the machine is built and compare it to conventional Toyota products for 'dust to dust' energy usage, then suck on the exhaust pipe of a Diesel car and try the same thing with a Prius.

in reply to the post on cars that get 55mpg apart from the prius here is afew

http://cars.uk.msn.com/greenmotoring/article.aspx?cp-documentid=1379476

@ Mark:

"clouds are transparent at UV ranges. It hardly ever blanks out the majority of sunlight either. We don't get huge deep nimbus clouds for long in the UK."

So tell us exactly what average percentage of power we can get when on a typically cloudy day compared to direct sunlight. UV isn't the only component of the received light (in fact in terms of energy it is a small portion of it), just as that wasn't the only factor that I had pointed out.

@ Frank Bough:

"Fitting a 50W panel into the roof of a Prius won't do anyone any harm, "

You miss the point, that might be correct but it won't do much use either - which is the original point: it's a PR stunt.

"and will help cool the interior "

How exactly does a 1kW hot roof keep the car cool? (while the solution to that might be obvious, it will result with the panel's lifetime being severely reduced).

PS: be careful about quoting drag coefficient, it is not a proper measure of drag.

Ultimately a Prius is a 1500cc hatchback that is very heavy. The hybrid bit distributes the power from that engine, maybe marginally better than a conventional transmission. Drivers on the A34 have been quoting about 38 MPG, about what you get if you drive a 1500cc car sensibly. In urban stop-start driving the hybrid bit should come into its own a bit more but ultimately the engine still has to do all the work to push it along the hybrid bit changes the route to the wheels a bit.

If you could plug it in at night you might be able to make a saving using economy 7 electricity but the sandal-wearing brigade will complain that's not 'green' either. Its made really for the American market so they probably won't try a diesel version either.

At the moment too much compromise for too little gain unless maybe you are a city driver when a Citroen C2 diesel would be more economical and kind to the environment

The weight seems to affect the Prius' handling as well. I watched one overtaking a truck on the A34 and it behaved like it had sacks of cement in the boot, seemed very reluctant to change lanes and seemed to need wrestling back in afterwards as well. The rest of us started giving them plenty of room... Then again maybe people who buy Eco-cars are not good drivers...

The solar panel's real utility (if any) will come if its parked up at the airport or other long term parking when it may be able to keep the battery alive to stop the alarm going off. Ask anyone who has worked at Heathrow parking. To be fair some cars, particularly luxury models could do with some help under those conditions.

yes solar panels are effectively greenhouses but then so are dark painted cars and that doesn't stop people buying them.

please do divide my result by 4, i did mention you could divide by 100 if you wish to allow for errors and as you can see just by sheer weight of numbers the actual surface area of 24 million cars is enough to collect a silly amount of energy.

And as for cost (if you're worried) no one seems to mind the extras that are added on for such luxuries as metallic paint work, go faster stripes, airbags, airconditioning (which is i admit mandatory in some parts of the world but not here in the uk, well it didn't seem to until about 10 years ago) all of which would cost a similar amount.

As for getting dirty and too much rain. surely the english rain would be useful for cleaning the tops of cars and hence keeping the panels efficient.

This may well be a PR stunt but someones got to start these things off. It won't make a huge difference to the individual (especially if you drive huge distances per year) but it will save fuel for the country as a whole and limit CO2 emissions. just as seat belts don't effect the individual (unless you crash) but if eveyone uses them then lives are saved.

and just as a side, where's this 10% nonsense come from for airconditioning? cars use a variable amount of fuel depending on what you're doing with them. A/C uses a fixed amount when on and nothing when off. so by stating 10% someone needs to qualify what the engine is doing (idling, racing, urban driving) and in doing so your % figure is rather pointless. using watts is a much more scientific unit.

is a journalist.

Need I say more?

Waves - "55mpg" comment; yes my friend, driven conservatively, the Fiat Doblo 1.9 diesel (mine is over 5 years old now) regularly resides over 60mpg. It's shaped like a brick. Difference is it also has a range of some 1000miles if I can be arsed to hold up the traffic.

Nigel - "like with like" comment; no, see above, a large 5 seater with oodles of boot space (my mates refer to it as the "tardis") - hideous to look at and almost large enough to fit a Prius inside.

Steve Evans - "lose 10% in fuel economy while driving with the windows down" comment; for the "average" car (God only knows what that means BTW) only once the vehicle is travelling over 80mph (100kph) will drag due to air turbulents cause an increase in fuel consumption greater than the air-con system. To justify air conditioning, one has also to declare that one is travelling at illegal speed.

Ash - "clipper lighter" comment; really nice analogy. I'll try to remember that one.

Terry Blay - "Continuously Variable Transmission" comment; LM(f)AO... the Honda Civic had that 20 years ago.

Glen - "Pope = Catholic" comment; I know this isn't the place for an ecumenical discussion but I have to draw the line at that assumption mate. He's a sith lord.

Aitor - "bike" comment; a(wo)men brother/sister.

Frank Bough - "read the broshure" comment - get real fool, that's the spin-laden advert designed to con people into buying that crap. These comments are real life experiences from people who live in the real world. Even with all those wonderful added fuel saving gizmos the Prius still only manages to come up to the same fuel efficiency as a much larger diesel. If you realy want to be transported by fuel efficent discomfort, buy a motorbike. It's infinitely more cool to be seen with too.

And I can average about 52mpg from it. It doesn't have a sunroof though, so the £20 one from Maplin would need to sit on the dashboard.

Note also that it has two batteries. One conventional one for the petrol engine, and one 200V NiMH one for powering the motor (which is charged during deceleration instead of just wasting energy in heating the brakes).

The air-con's a bit pants though, can take ten minutes to cool the cockpit on a sunny day - so something that could keep the fan running when it's parked, with or without air-con, could be a benefit.

Oh, and road-tax is £15/year. What is it in your 144mph diesel BMW? Don't forget that diesel has a lot more carbon in it per litre than petrol...

Try one before you slag it off. They are a bit bland and grey (mine is *actually* grey) but they drive just like any other (automatic) car out there. There are no compromises on performance (it's about the same as a 2.0 Mondeo) and it's comfortable and quiet. I didn't buy mine to save the planet, I bought it because it's a very clever piece of engineering. I average low 50's mpg (that's UK gallons for all you dopes who didn't spot that some of the posters were referring to US gallons) around town and high 50's on A roads and Mways. Best there and back journey was 63 mpg central London to High Wycombe and back, same day, not very windy, sticking to about 60 on the motorway.

I thought YOU were the knowledgeable one. Or were you pulling arguments from your arse?

I've owned a Prius for two years and put 30k miles on it. It's got all the power and performance I need to crank 70mph on I-90 in Seattle. I AVERAGE 52.5 miles per gallon. In 30k miles, I've rotated the tires a few times and changed the oil every 5k miles.

What the fuck is wrong with that? NO OTHER CAR ON THE ROAD COMPARES TO THAT, and those are the straight facts. Wake up, losers.

I am surprised at the emotions generated on this comment section. Come on people, we're just talking about automobiles here, not your daughter's prom date! Many of you seem to think this is some sort of competition. I am pleased to read there are cars across the pond, that get gas mileage comparable to a Prius. That is good news for everyone. I've been saying all along, that my 55 mpg Prius was using US gallons, not Imperial gallons. I also foolishly assumed you guys over there were converting to US gallons. How presumptuous and American of me, huh? Sorry about that. Hey are you guys still driving on the wrong side of the road? Just kidding! I'm glad someone actually took a second to do the conversion. I guess it works out to be 66 mpg Imperial. By the way, the comment about my F-350 truck getting 11 mpg was only meant to lighten things up a bit. I wasn't really comparing my truck to a Prius. Come on! I'm glad so many Prius owners backed up my mpg claims. Thank you. And as far as a fully loaded van getting that kind of mileage, well now I am the one with doubt. In any case, in the US, there are no production cars, vans, or trucks made OR imported that can achieve the gas mileage of a Prius. Maybe someday we can catch up with you guys over there and get fully loaded vans that get 70 mpg, but currently, we have no such vehicles here. As a side note, historically in this country, diesel fuel has been much lower in price than gasoline. Even though diesel costs much less to refine, it is now much more expensive than gas or ethanol fuels. I think it went up because I bought my diesel gobbling truck. ha! Yeah, I know, you guys over there pay much more than we do. That sucks! Last time I was over there, I was shocked at how much you guys must pay for a gallon of fuel. Fuel cost in Japan is even much higher. Hopefully these outrageous costs will keep the engineers working overtime to make a car which will get an honest 120 mpg that we can all be happy with. We shall see. There are a couple of companies planning to sell fuel cell cars in California. Hope it works out.

P.S. Once again, unless it is a new option I haven't seen yet, the Prius does not come with a sun roof, or roof rack, so mounting solar panels in the roof should not pose a problem for the manufacturer.

All for now. Waves

I forgot to mention to the Prius owner with a lethargic aircon. I live in a dessert where the temperature routinely reaches 105 degrees F. The aircon in my Prius truly works great. You may want to have the dealership check the system for proper operation and/or possibly a low freon charge.

@ Mark:

Ah the old fallacy of tu quoque mixed with ad hominem. If you cannot stand by your statement then please don't act disingenuously. Don’t forget that I mentioned several factors, not just that one which you have again cherry picked...

@ Jimmy:

You are right about the dark cars, but that's a diversion and doesn't take away from my point - which is amplified if we're to consider all cars and vast fields with these things (as they currently are).

"the actual surface area of 24 million cars is enough to collect a silly amount of energy."

Yes, it does seem a little silly when that energy is distributed among 24 million cars!

“no one seems to mind the extras that are added on for such luxuries as metallic paint work, go faster stripes, airbags, airconditioning”

At least one gets something desirable and/or useful (the luxuries), I can’t say the same for the panel.

Rain does not shift the dirt from my car (yes I made the mistake of buying a white car, anyone who owns one will tell you that rain doesn't do jack).

Yes, someone has to start these things off, but let's start with something useful, not a PR stunt which claims to be something which it isn't. The more times the environmentalists cry wolf, the less likely society will believe them when there actually is a real problem – that’s what will kill the planet!

Oh yes, it wasn't me who stated 10% in term of air con usage - I actually stated that the whole concept was flawed from the start (hot roof anyone?)

No, you made a pronouncement and then wanted education over it. This would indicate you made a pronouncement from a position of ignorance.

If this is not the case, then, please, your reasoning.

Big words not confuse me.

PS: Generally, not for you Steve, if you have a car in good nick that's less than 15 years old, KEEP IT. Tune it up, even. Get it rebored, get the timing looked at, give it a couple of grand engineering loving. It will get better mileage than it did before, better emissions, better performance and you won't have to scrap it and bring in the cost of making a new car.

Just don't drive it without the tender care because it will become a heap of shite.

What a cock, more like.

Look at your own posting.

Did you think that learning the sun wasn't always overhead was an astounding revelation? "OMG!!! The DayStar is not directly over my head all day, everyday!! My calculations RUINED!!!!"

I suggest to you that this is not the startling news you think it to be.

Now, think also of this: the square metre in the UK is not directly under the Sun either. Nor is the ground tilted to face the sun directly. Therefore, measurements of how much solar energy that hit the ground in the UK may take such geometrical configurations into account.

I know it's a wild stab in the dark.

by coincidence i;

a) ordered a 30 watt polycrystaline solar panel last week

b) was talking about this idea the day before the story was released (freaked me out a bit, hence my interest)

Anyway, the solar panel arrived today and as per usual it was raining in manchester. It's now charging a 12Volt deep cycle battery in my shed (i'm not going to strap it to my car!). So in the rain in summer it kicks out about 400mA facing straight up (not angled to the sun). It's about 75cmx35cm and i reckon i could fit 10 of those on my BMW compact (if they were built into the body work of the roof and bonnet).

so that's 4amps at 12 volts or 48 watts. but obviously you'd get more in the sun and less in winter. 10 of those panels would cost £500 at todays prices.

You'd lose a 3rd charging the battery so that's 32 watts. assume 8 hours daylight per day. you'd earn: 32x60x60x8x365 joules per year of useful energy = 336.4 MJoules. 10% would be lost converting this back into kinetic energy via electric motors. so that takes you to about 300MJoules per year.

As per my comment above petrol gives 7.5Mjoules per litre of USEFUL kinetic energy to the car. so 300/7.5 is 40 litres of saved petrol per year in manchester for an average sized car. or about £50 per year. So it'd take at least 10 years to earn your money back.

That's the bad news i suppose. but AT LEAST YOU EARN SOMETHING BACK which i'm afraid to say you will NEVER do for anything else you buy for your car. It'll keep earning money back for you as long as your car is working. i may be a bit weird but i'd rather spend money on this than a personalised number plate or metallic paintwork.

but back to my point 24 million cars x40 litres is about 1 billion litres of saved petrol/diesel per YEAR. You can't argue with those kind of figures. The only other thing that's saved that much petrol is doubling of the price of fuel and we all know how much extra money that is costing us (i dare say more than £500 per cars lifetime that solar panels would cost).

i wonder what our world would be like if all cars had to be sold with solar cells incorporated into their bonnets and roofs (and somehow hybridised or pure electric engines)? Would it be so bad? After all we have worse things imposed on us. eg. 'green' taxes that seem to do nothing but hamper our lives.

@steve:

are you seriously suggesting that solar energy once it's passed through the atmosphere will not escape again if we coat cars in solar cells but if they have normal paintwork the solar energy will magically be allowed out of the atmosphere again? dark materials are excellent radiators of energy and it's the greenhouse effect of upper atmosphere chemicals which i understand to be the problem.

looking at my aging BMW outside it does look a little dirty (it's dark green) but since i haven't washed it for about 3 years it seems to do ok considering. All that manchester rain i suppose.......................

didn't mean to accuse you of the 10% thing, sorry!

@Chris who seems to have all the condescending answers, hates everyone, and says: All you do is save your pollution for the countryside. Thanks a lot. You kill baby foxes with your stupid Priuses, choking them to death on your sickening fumes. Jerks.

What the hell are you talking about Crazy man?

@John Robson who says: The American market doesn't seem to understand what an engine can do, and doesn't care about oil, because they'll just go and invade somewhere else.

Your're probably right, but that's a fairly odd statement coming from someone in the UK where they used to boast about how the sun never sets on British soil. How did you guys acquire all of those territories anyway? Yeah, I know, it was a long time ago. Hmmm, anyone remember the Falkland war? Anyway, after reading your post a bit slower, I realize you claimed 53 mpg Imperial, not 70. My mistake. I'm still amazed about your van's gas mileage of 53. Not the 66 mpg Imperial that I get with the Prius, nevertheless, quite impressive.

This comment section is getting a bit too hostile for us rational folks. Later

""read the broshure" comment"

That's "brochure", cretin.

"- get real fool, that's the spin-laden advert designed to con people into buying that crap. These comments are real life experiences from people who live in the real world. Even with all those wonderful added fuel saving gizmos the Prius still only manages to come up to the same fuel efficiency as a much larger diesel."

No it does not. If you could be bothered to read the specifications of the Prius you'd learn a little about what it's designed to do, how large/heavy it is and directly comparable it isn't to a carcinogen-spewing Diesel powered car. The Prius is designed - essentially - as an urban/suburban commuter box, a job which it does in a very civilised and efficient manner. It's not a sports car, neither is it a long-distance repmobile.

"If you realy want to be transported by fuel efficent discomfort, buy a motorbike. It's infinitely more cool to be seen with too."

Yeah, sure, if you're 16 years old.

"But you did it too" went out at playschool as a rebuttal.

One would have thought someone trying to present themselves as a reasoned individual would refrain from schoolyard disputation.

PS: That would be nearly three generations ago that the British left the Empire. I can hardly see that bringing this up against a contemporary reflects in ANY WAY to reduce the validity of the accusation. Nor does it seem to require the recipient of the slur to change in the least: THEY never did that, so what's to change?

Well well, trying to divert again are we. Why don’t you give me the education that I asked for instead of acting so silly? I could apply your quote of 8th July 2008 14:37 right back at you (which would be correct when considering your statement about the UV).

If you still cannot state what portion of power is still received then all you had to say is that you don’t know instead of making your stance look even more desperate. Your second post is still cherry picking, there are yet other factors which you somehow missed. All these factors ADDED TOGETHER make a significant difference – something you still don’t seem to understand or accept.

“Therefore, measurements of how much solar energy that hit the ground in the UK may take such geometrical configurations into account.”

You say ‘may’, so don’t you know? Solar panel manufactures always state the output power assuming optimal usage, they leave the trivial utilisation calculations to the end-user – unless you believe they ship them stating a correction factor for each country <boggle>

Regardless, the earlier calculations I referred to had obviously assumed perpendicular incident light.

“So it'd take at least 10 years to earn your money back.”

Thanks for your calculations (at least someone seeks to justify their opinion). An additional problem is that the useful lifetime of solar cells is finite. Quality cells last about 20 years but the power output starts dropping off way before that; hence it may never pay for itself – even if your car keeps going.

“You can't argue with those kind of figures.”

Actually I can. The cost saving is offset, likely completely offset, by the amount you pay for it. The oil saving will be offset (by what amount I don’t know) by the resource (not just oil) used to extract/manufacture/transport it. Modern cells are indeed net energy producers, but only when used optimally. As I have already highlighted, in this application the usage is far from optimal.

RE greenhouse effect: apart from the fact that you seemed to have assumed that all paintwork will reflect back (or course it won’t) - that’s exactly how it works. Today’s inefficient solar are indeed excellent radiators of heat – at different (much longer) wavelengths than what is received. The received light passes straight through our atmosphere (apart from the UV, something which still hasn’t clicked with Jimmy), but the re-emitted IR doesn’t pass straight back through.

I’ve had sections of my white Toyota totally blackened out during prolonged wet phases (yeah, that was funny to see); saying that my panels are usually a shade of brown. Your dirt could be absorbing all the red and blue wavelengths (even some of the green) leaving the green to bounce off your dark green paintwork and you wouldn’t know it. Why do so many people regularly wash their cars when our ever recurring, cleansing rains are so good at the job!

“i wonder what our world would be like if all cars had to be sold with solar cells incorporated into their bonnets and roofs (and somehow hybridised or pure electric engines)? Would it be so bad?”

Of course not, but as I said before, it is a bit pointless when considering that power/resource saving is the aim of the game (based on today’s cells). Now there IS a legitimate use for such panels, but seeing as I’ve seen no mention of it anywhere I might go off and patent it (don't think I'm kidding, I've spent today writing one [for a different field]).

1) How do we know todays cells won't last more than 20 years? The cells made in 1988 are by far inferior to todays (especially in efficiency of converting light to electricity). i was under the impression that there was no agreed lifespan due to these factors. current estimates are 30+ years.

2) RE greenhouses. i do have a grasp of this. i understand most UV doesn't make it through our atmosphere (otherwise we wouldn't be sending UV scopes into space) but some wavelengths do get through otherwise we couldn't get sunburnt.

Yes radiation is mostly IR (black body radiation at 15C) and escapes mostly when it's clear (clouds are great greenhouses). CO2, methane and others are good at reflecting IR too, that's why we're trying to reduce these being emitted. I don't see the difference between solar cells and car paint though. Yes they're slightly different colours but will it make that much difference?

3) good point about the green car. but with everyone washing their cars so often (i've always considered it a waste of time myself) surely this cures the problem (i guess i might be motivated to wash mine if it was costing me fuel!)

4) As for cost. I was proposing mandatory solar cells just as airbags, seatbelts, fog lights, headlights, car tax etc are mandatory. so earning your money back would not be an issue, but it would be a bonus to leave your car in the sun more.

5) As for earning your energy back, 1-4 years is what i've heard for modern cells (used optimally), which isn't great considering most cars only last 15yrs or so. Amorphous cells are a lot cheaper and easier to make (but are less efficient), they even come in flexible foil these days so you could just stick em onto ya car like doublesided tape.

you're right though the economics are a bit dodgy at present but it's probably a close call. which means in my head that someone needs to do some research into this. So if Toyota wanna take this up then good on em and i wish them well.

The main problem is the vested interest in making this NOT work by several MASSIVE companies/industries. Which i suspect is the main reason why a) there have been no electric cars of note and b) this idea will never become a reality. sad really. AND c) why the stupidest idea of the lot (hydrogen fuel) may well reach reality as it is an ideal fuel to tax and regulate but is awful in all other respects.

I'm getting a Tesla when they're out and sticking solar cells on me house roof.

Sorry Mark, I guess you didn't get my humor! My comments to Chris and John were not meant to be jabs per se. Inflection is sometimes difficult to show in an email. I also didn't expect or ask anyone to change anything, so I'm not sure where you were going with that one. As far as John's comment, I stated that he was probably right, followed by some light humor. HUMOR COMING--If the UK had any oil, we would probably invade you guys as well. Hey you invaded us once!

As far as Chris' statement about killing baby foxes with my Prius, and saving all of my pollution for the countryside, I'm still trying to figure that one out???? I thought calling him Crazy man instead of a f*%@ing idiot would keep me off the playground, but I guess not. Sorry. Maybe I should have instead said that his statement sounded as if it were coming from that of a ranting crazy man. I certainly agree with you that calling people names is a huge mistake when one is trying to make a point.

Fortunately, I am not trying to make any points here. I am just a Prius owner trying to share with others some info about the car. I never dreamed there would be so many Prius experts, and Prius haters, most of which have probably never even driven one. I am also surprised at the non-Prius owners that are so negative and close minded about the car. I truly don't care what you, or my next door neighbor drives, and I'm not trying to save the planet with my Prius. I like the car, and it works great for me. That is all. You guys continue driving what works best for you. So, I will refrain from calling all of you MF people any names again.

Anyway, the original subject now seems to be lost, and it is apparent that I am also ranting. All for now. Waves

P.S. 1 By the way, the MF stands for "mighty fine." Gotcha!

P.S. 2 They tell me that my F-350 will get better mileage (about 13-15 mpg US) once the engine is broken in. I checked, nope the parking brake wasn't set. Nope, no trailer either. Darn those twin turbos! It still gets 11 mpg US! Actually, when the trailer is hooked up, it gets about 8 mpg US. It sure has tonnes of power though.

You keep trying to pass off questions. If you don't know the answers, just say so. you manhood won't shrivel.

1) Current estimates are 20-30 years for the latest generation quality cells, but I very much doubt Toyota would spend that much money on the latest and greatest tech (especially as it won’t be used optimally).

2) Yes some UV gets through (about 1/3 to ¼) but others (who I will no longer let bring me down to his level) seem to think that clouds being transparent to UV will make everything OK even though the UV accounts for less than 5% of the useful energy received at sea level.

As I already said, I don’t believe this additional panel will do much to reduce the CO2 footprint (if you believe we should be doing so).

The difference between solar panels and (non-dark) paint is that paint will re-radiate mostly at 3000-6000 K, not 300K (visible wavelengths, not IR).

3) I said ‘many people’ wash their car, not “everyone”; now everyone with a panel would have to (to aid towards optimal use) – which was my point ;c)

4) Airbags, seatbelts, fog lights, headlights are all useful (some in certain circumstances), they help prevent occupants (and other road users) from dying, so on average they all add significant value even though they don’t earn money. Car tax and this additional panel aren’t useful, don’t add value but yes: they do earn money - but not for you. Leaving the car in the sun more will completely kill the argument about the benefit to aircon (hot car). Also, doing so will also accelerate the decay of the cells and paintwork. When the car is not being driven and it’s not used to charge or power something at maximum possible panel power, what’s exactly is the point of keeping it in the sun when not in use? The engine will have already topped up the battery (it has to otherwise one risks not being able to start the car). All it will do give ~1W to power the alarm and battery and convert the other 99% of the energy to IR and heat.

Damn that is a good point; for me that completely kills the utilisation and payback aspects.

5) Expensive but efficient panels, accounting for non-optimal factors, will result with insignificant payback. Inexpensive but inefficient panels, again accounting for non-optimal factors, will result with insignificant payback. Either way it doesn’t work with today’s tech. If people want to make real use of the energy they provide then they should rip them from those cars and use them more optimally, like strategically placed/angled roofs, or better yet on motorised beds, not on cars.

Now I think of it, this is where the harm is. The false notion that these things are useful has resulted with misallocation of what would otherwise have been a useful energy resource. Regardless of panel efficiency, we should wait for panels to used on all houses before we even consider mounting them to cars; the latter also being at significantly greater risk of breakages through crashing or vandalism – or even being stolen!

Couple that with the fact that you’ll never utilise full possible power anywhere near the maximum possible time (when mounted onto the car), it’s a dead duck. In fact, it's likely that the use of it on a car as increased the CO2 footprint (negative 'net energy') - how ironic!

Oh how I laughed when I read your "carcinogen-spewing Diesel powered car" rebuffal. The diesel engine spews carbon (visible dirt rather than invisible dirt). For real carcinogen (cyclic aromatic) release you need to purchase and drive a vehicle that incorporates an unleaded petrol engine, like the, er... um,... ;o). How pious, the Prius owners have become. How narrow and misinformed their *brochure* dependent minds have become; how typically pedantic your assault on my typo was. Face it d00d, you bought a ringer. We all make mistakes, yours at least was made from the very best of intentions. Stick with it now you have got it though because it would be even more environmentally unsound to trash the vehicle. It's not a dig at you, it's not a personal character assassination, I like the idea of the dual fuel, inertial recharge, solar panel enhancements that are being tested out but the technology is still far behind the dream... This is one person's opinion - or don't you subscribe to the declaration of human rights?

Is it a legal requirement to give up your sense of humo(u)r when you buy one of these things?

Are you saying that solar cells should not be left in the sun because they degrade? Now that is a ridiculous thing to say! They're designed to be left in the sun!

So i'm not suggesting these should be retrofitted to existing cars, that would be pointless. New cars (whether hybrid like the Prius or pure electric like the Tesla) will need to be fitted with adequate spare charging capacity so that as much energy as possible is stored from the cells when the car is not in use.

Unfortunately the Prius does not do this, whenever the petrol engine is in use it's charging the battery to its max (a big downfall i think as this is inefficient, the energy would be better off being used to propel the car).

So my main points are these (and i don't think anyone can disagree with them):

Firstly, it must be demonstrated that car solar panel manufacture takes up less energy than they generate in their average lifespan.

Secondly, cost to the consumer is not a necessary consideration. Think catalytic converters. Mandatory, they add several hundred pounds to the cost of a new car, they REDUCE fuel efficiency (by necessitating an increase in the fuel/oxygen ratio therefore more fuel is used) and they do nothing (except cost money) for the individual driver. They only act on mass to improve air quality.

Thirdly, i therefore see no reason why this concept can not become reality at some point. It will eventually save money for the driver as compared to other mandatory car features.

I agree that putting them on houses will use the cells more optimally than cars though. But i'm afraid household electricity prices are going to have to be in the same realms of petrol prices to make them economical. Something that WILL happen in time if no one does anything about it, we are after all at peak oil production.

Either that or hybrids are going to have to become 'Plugin' so that you can use the energy from your house solar cells to charge your car. This involves adding more battery energy storage to extend their range and also increasing the top speed at which they run solely on electric. The problem with this is that cars are usually away from home when the cells are producing most energy. The energy has to then be sold to the grid for (cheekily) less than you buy it back. someone needs to do something about that.

Car manufacturers seem a little scared of producing plugin hybrids probably because the amount we rely on petrol might crash, the government would earn less tax and influencial oil giants would lose money.

As for your suggestion of having fields of panels tracking the sun to optimise efficiency. Not good for the UK where we're struggling for space. I doubt it'd get past planning either. Great for the sahara though, but then you'd lose a lot of energy transporting it thousands of miles.

how's your patent going?

It would be a strawman fallacy to say that I implied “solar cells should not be left in the sun because they degrade”, I said that it would be so if the cells are NOT IN USE (or at least not used at a decent power output). They will still degrade when left in the sun even if no power is taken from them.

“ New cars (whether hybrid like the Prius or pure electric like the Tesla) will need to be fitted with adequate spare charging capacity so that as much energy as possible is stored from the cells when the car is not in use.”

Agreed, but that makes the payback/CO2 footprint situation even worse. This requires a bigger, or more likely, a second battery must be used. Current lead acid devices last about 4 years before their capacity tails off.

“Unfortunately the Prius does not do this”

Exactly, it is a PR stunt!

The picture is bigger than simply saying “it must be demonstrated that car solar panel manufacture takes up less energy than they generate in their average lifespan.”. The panels will be utilised only when the car is being driven, if not then consideration must also be given to the resource needed to store the otherwise ‘unused’ energy.

The only real considerations are cost to customer and net oil use (which inherently includes CO2 footprint). I think we can now discount cost, especially as Toyota won’t charge the customer at the cost of the cell. Oil is debateable due to the resource (not just oil, which isn’t the only unsustainable ingredient) needed for the cell and multiple, relatively short lifetime batteries.

Again considering the bigger picture: the ‘other mandatory car features’ will save money by helping to prevent accidents, deaths and other health issues. This reduces police and hospital bills (and ultimately the cost to the taxpayer) and insurance costs.

The government would not lose money if we all used electric cars, they would continue to screw the motorist by rolling out a congestion charge, which is exactly what they’re already trying to do. I’m ambivalent about oil giants losing money; I would be much happier with no longer funding unstable and inhumane regimes.

Please note, I didn’t suggest we should have ‘fields’ of these things, I mentioned the issue merely for warning about large scale heat trapping.

I agree the concept of panels on cars could become useful when more advanced tech becomes available and cost effective, but today’s PR stunt is a false economy and is resulting with misallocation of resource.

I’m in the midst of taking legal advice from patent lawyers.

How does new tech become cheaper? By early adopters buying it when it's new and expensive.

E.g. CD players. DVD players. VHS toploaders. *cars* themselves.

I'm not saying we should avoid such devices, I never have (that's a strawman fallacy); I AM saying we shouldn't be misallocating what could otherwise be a useful resource.

"I agree the concept of panels on cars could become useful when more advanced tech becomes available and cost effective, but today’s PR stunt is a false economy and is resulting with misallocation of resource."

The second half of the sentence looks like a run-on and doesn't seem to have any connection to the earlier half.

“Useful …” against “false economy…” – meaning ‘not useful’; there’s your connection.

I can’t say I’m concerned with your comment if that’s the most significant gripe you have with my arguments; it’s not like your own arguments and behaviour commanded respect anyway!

Unless your future comments sincerely add to the debate I will refrain from responding to you, so feel free to end with the inevitable silly parting shot.

It seems like this debate has concluded anyway.

Come on, you must agree that the statement doesn't LOOK like what you said you meant.

You do realise that you are not increasing your MPG, you are merely not using the engine for part of the distance traveled, therefore not using the fuel ?

There is no greater fuel economy gained from your engine, just more fuel used somewhere geographically different.

I can buy 5 litres of petrol and keep it in a can in the boot. I can drive to John 'o' Groats and back without using it at all ! How's that for MPG ?

You should be focusing on total energy used for the distance travelled, however and where ever it was generated.