An electric car with 100mi range would be great for the daily commute.

Well, for normal drivers at least. Just think, how many miles would the average punter cover in a day? Assuming that your travelling salesman type drove it every weekday right up to the 250 mile limit, that works out at over 65,000 miles a year. Given that the average yearly car mileage is supposedly more like 10,000 miles, the average daily mileage is under 28 miles. Admittedly, we're not all average drivers and yes, we may need to drive more than 250 miles in a day once and again but the fact is that for the average driver, I believe that 250 miles would be more than enough.

And yes, the Tesla is expensive. $100K is a lot for a sports car and the competition at that price level will beat it. But remember, the Tesla is the first to provide this type of performance in a battery car. There will be others. The technology will be patented, copied and will appear elsewhere in cheaper cars. The cost will come down and the technology will improve. For a start, lithium-ion batteries have only been commercially available for 16 years ... imagine what battery chemistry will be around in 2023, especially when the need for more efficient batteries becomes more pressing due to lack of fossil fuel.

Don't be so short sighted! Think outside the box once in a while, you might enjoy it.

One other thing that wasn't mentioned was the small matter of parking. It's all very well for those people who have a garage to store their car, or a drive way next to the house, but what about those people who park their cars in the street, or somewhere else where they can't be sure of having the same space each time. How are they supposed to charge the car during the night.

In fact I think this was something that Top Gear eluded to a while back when they did a piece on electric cars, and tried to charge the car with an extension cable out of the house, across the pavement to the car, with obvious results.

You're right about batteries and you may as well lump hydrogen in there as well. Producing hydrogen surely requires far too much energy to make it a realistic fuel for the masses.

That leaves us with two options:

1.) Fossil fuel, which will run out and, through its combustion is causing the global climate change which we are concerned about.

2.) Biofuel. Bio-fuel is interesting because the raw materials for bio-fuel production, photo-synthesizing plants, are busy taking CO2 out of the atmostphere. The technology is already available and used. Petrol equivalent can be produced from ethanol from a variety of sources. Contrary to what the oil companies and car companies tell us (not that they have vested interests), most diesel engines will run quite happily on vegetable oil with little or no alteration to either the oil or the engine. There's the old chestnut of "it will take far too much space to grow the crops required" which can be countered in a number of ways. Phytoplankton could be genetically modified to produce oily secretions - and genetically modified only to mate with each other to prevent contamination of the gene pool. Oil producing plants can be encouraged to grow in hostile climates using advanced irrigation techniques and selective breeding. We could even work out ways of cultivating oil plants in vertical tubes to try to maximise yield / area.

Or we can keep building silly battery cars and silly hydrogen vehicles and fiddle while Rome burns

The problem with this, and any other electric car, is that at some point you have to charge it up. And right now when you do that you're probably burning coal/gas/oil to generate the power, so you're still chucking a load of CO2 into the atmosphere.

Until we sort out clean power generation the electric car is not going to be a practical solution - biofuels and hydrogen are the way forward in the meantime.

Realistically petrolheads that want to do 130 or more are not going to be interested in buying an electric car. It's a good attention seeker and demonstration of just what an electric car can achieve though. More realistically this technology will be used by greater numbers in slower and more practical vehicles for urban and suburban short to medium distance regular commuting, school runs and shopping. It would also be nice to see milk float tech improved and lightened a bit to suit the white van operators out there. Questions to ask are how much and how fast can lithium ion be put into production volumes and what the other environmental issues of manufacturing and recycling these units will be ? Also whether the manufacturers can standardise the shape, size and loading bay options so the batteries can be lifted and plugged in and out using robotic fork-lift devices at the filling stations, so changing one of these is no slower than handing in an empty gas cylinder and getting a full one ? Then the battery life isn't an issue, because you pay a small share of the recycling of the thing each time you get a replacement. Need to go further than 250 miles in a day ? In that case get on a high-speed train and hire a car at the other end.

Despite the disagreements I have with your post, Tesla Motors makes an excellent business case. As long as their car delivers as advertised, I'm convinced they have sufficient demand to justify their product. The success of hybrids, high gas prices, and current political climate only help the company's cause.

I don't expect, nor do I expect the vast majority of the driving public, to be driving over 130 mph and 250 miles on a daily basis. People who buy this car are going to have a standard gas-powered car in their garage.

This is marketed as a sports car and produced in limited numbers, but I think you fail to see the ultimate goal of Tesla's product -- the eventual production of a family sedan priced around $50,000 (and then one ~$30k a couple years later). The roadster is intended to generate viral marketing for their next generation car...and it's working. And there are plenty of people who can afford this car in the first place. It will happen slowly, yes, but how many Toyota/Honda hybrids have you seen on US roads recently?

Your criticism of the technology behind li-ion batteries is incorrect as well. There have been incremental improvements behind the li-ion technology, and they occur constantly...and they are getting cheaper.

Electric cars may be an imperfect stopgap between gasoline and biofuels/hydrogen, but the value created is well within the 99% of household driving needs. I am surprised you see it differently.

In New Mexico, I commute 28 miles each way to work and back, 5 days a week. I might stop in town twice a week after work. On the weekend, I only go on a long drive (more than 50 miles from home) maybe once a month. Now, if they could just get the price of a Tesla down to what I paid for my '70 Impala ($3000), I'd be set. It can do 0-60 MPH in 5 seconds and a 12.3 quarter mile but only gets 10-12 MPH. Darn those 454 ci engines! And it only gets about 250 miles a tank of petrol.

So each car needs a 900lb (wassat in proper units - 400kg)

battery. For the sake of argument, let's say there's 100kg of

lithium in each one.

Now multiply that by 600 million cars in the world, comes to

60 million tons of pure lithium. Hopefully each battery will last

10 years and 90% of the Li is reused. That's 600,000 tons of

metal per year.

In the whole world, we only extract 80,000 tons of Li per year,

once we get to the steady-state of replacing all the petrol

cars with electric. You won't get a six-fold increase in

production without a crushing increase in the price.

Putting aside the environmental costs of all the refining and

transporting of a highly reactive metal, will we become

dependant on the Lithium producing countries, the way we

are now on the oil producers?

After all, (jet)planes are massive polluters. What will their next power source be? Can't see them sticking battery-powered electric fans onto the wings anytime soon!

A point supporting electric cars.

An idea recently discussed in the journal Nature proposed that electric hybrid cars form a part of a distributed energy generating system. In this system your car supplies energy back to the grid at time of peak evening demand; to power your kettle during the Coronation Street adverts, and later recharges at time of low demand. Considering that an estimated 20% of power generating capacity is there just to meet peak demand, this would have a significant benefit by reducing the need for additional power stations.

Of course this would only happen if the government encourages distributed and microgeneration technologies.

The range of EV's would be a non-issue if we conceived of and implemented battery exchange stations in the same way we have gasoline stations. The concept is extremely simple, when your battery is running down you stop at an exchange station and in a matter of minutes you have a fully charged battery and you are on your way. Check out the video at http://digg.com/tech_news/Electric_Car_Battery_Exchange_Station_video

good point Pete.

My previous post from ‘Carmakers tout green motors in Geneva’

Couple points about lithium batteries.

1. Only 4 countries in the world have lithium.

2. GM Volt, electric plug in car which uses lithium batteries, had very inconsistent battery life ie 2 months to 5 years!

3. Electric cars sound great but Northern Hemisphere countries with cold climates are not suited to batteries. Try starting an electric car in 30 below and the performace of the battery is reduced by 50%.

Traffic Flow:

If we could slow down the traffic but not make it stop would save more than 50% of the energy (electric, ethnaol, etc). In Sydney I stop for every 8 stop lights out of 10....

Cheers

After having watched "who killed the electric car" recently, Im convinced electric cars do have a place in society now, and are good for most regular users. I quote from the movie "its true that electric cars are not for every one. They only suit the purposes of 90% of the population". Plus in the movie they were using NiMH batterys, the cars were fast and quiet, and they pictured people parking outdoors (again wouldnt work everywhere) under large solar panel parking areas, to plug their car in and go in to work for the day. Now if thats not an awesome idea when it can be done I dont know what is! Electric cars? Bring them on!

Seriously, you lot are all narrow minded.... What's with dismissing an alternative fuel just because it doesn't suite every single person?

Do you lot all live in a place where everyone drives the same vehicle? No.

You should buy vehicles to suite your needs (although how many city dwellers have 4WDs with no reason?). If a limitation of 200km trip before requiring a 3 hour recharge is an issue, you don't buy the thing. On the other hand, if you drive 100km a day max, and then have all night to recharge in your garage, it's clearly suitable (at least as a second vehicle).

> Do you lot all live in a place where everyone drives the same vehicle? No

actually Tim, the answer is "yes". Here's why.

All the vehicles we drive now (I've never seen a hydrogen or ethanol powered vehicle, so I'm dismissing them. Maybe I'll change this in the years to come, but for now it stands) use basically the same fuel and it's delivered using the same technology, from the same source.

Whether it's petrol or diesel, the product is oil based. It is refined and delivered using the same route and is dispensed in the same way. It is stored in the vehicle as a liquid, in tanks and is used to provide power in the same way: i.e. combustion.

Electric vehicles share none of these common elements with petrol/deisel, so compared with the subject of this topic, yes all the vehicles we drive are the same.

One interesting solution to the range of electric cars (and charging, and congestion) can be seen here:

http://www.ruf.dk/

Simply using electricity doesn't actually help that much. All that happens is that carbon emissions are shunted back to fossil fuel power stations. These are still the prime sources of energy in the UK, and most of known civilisation. Furthermore high efficiency electric motors tend to use the most powerful permanent magnets they can. The best of which use the rare earth metal neodymium, which is costly to refine.

So therefore would someone please tell me how a Toyota Prius, assembled in the far east, shipped half way around the globe, utilising a difficult to extract rare metals and using electricity as power source (one that at point of consumption i.e. the wall socket is only a few percent efficient after generation and electrical transmission loss) is better for the environment, because I'd really love to know.

"Barring a sudden leap forward in high-temperature superconductors or something else out of left field"

Like the recent discovery/ Production of single atom thickness carbon sheeting, which has many high temperature semiconductor properties????

As I see it, there are two problems:

1. These cars are way too expensive

2. I may only make a 200 miles + trip twice a year, but I DO want to be able to make that trip.

As I see it, the simple answer is plug-in hybrid cars. A car with a battery big enough to make 100 miles and a small, efficient almost constant speed ICE attached to both a power generator & CVT is the answer:

-You use it as a "regular" electric car for your daily conmuting.

-You can make trips beyond the electric range, and very efficiently (more or less double the usual gas efficiency).

-The car costs almost the same as a full electric 200+ mile range car, as you have half the batteries. Note: when I say almost the same, I mean they should be a little bit LESS expensive.

Currently I'm working on a DeLorean conversion that will run on household rubbish...

Seriously though the dream of pretty much limitless, polution free energy is some way off yet. The question we should be asking is whether the planet can stand the population growth until we reach a technology point where we have cleaner limitless energy...

According to these people electric vehicles are a no-no:

http://cnwmr.com/nss-folder/automotiveenergy/

Given the overall inefficiency in production, transmission and storage of electric - particularly in battries... The overall efficiency of electric cars is probably much worse than petrol, diesel or lpg.

Remember it likely still uses electric from a coal or oil power station - thus pollution somewhere.

As for ethanol - presently, it consumes more energy to harvest, make and deliver than it produces. Also, vast amount of land (i.e. where we grow food and rainforests) would be needed to make any meaningful contribution to our energy needs. Though - we could use it in planes when the oil does run out.

Oil is just too useful to burn more than you need on the drive to work. Apart from the CO2 story... (which might not be causing global warming, checkout - An experiment that hints we are wrong on climate change, The Sunday Times 11/2/2007)

Let's hope the boys at ITER get their fusion reactor going before the lights go off... www.iter.org

Electric cars are, and will remain for the forseeable future, a polluting technology. Ignoring the batteries and the energy/meterials required to make & recycle them, they require a source of electricity and several energy conversion stages which all have a finite (<100%) efficiency. I don't know all the figures, but I doubt if there's much difference in well-wheel efficiency.

Ahh, but we'll use <insert clean supply technology> to charge it. That is just a smokescreen. If you have (say) 10kW of solar energy available, then you can do two things with it - use it to charge your car, or use it to reduce the amount drawn from the grid. So anything you put into the car is electricity that could be used to reduce the amount generated from fossil fuels.

Only by putting in NEW non-fossil capacity to feed the car can you really avoid this situation - but then, it might just be better to feed that into the grid, reduce the use of fossil fuel burnt at the power station, and use the fossil fuel in the car. The only difference is where the CO2 is emitted - at the power station is the bit usually 'conveniently ignored' by the pro-electric camp.

The point people seem to be missing here is that although a car like this covers your needs almost all the time, this is NOT enough. I have a 10km commute to work every day, and in the weekends I occasionally visit my parents 100km away. Perfect usage pattern for a car like this. But does this mean that I condier it an option? No. Last weekend I went skiing in the mountains. Out of range of that car. Last summer I drove through half of norway and large parts of Finnland and Sweeden for vacation. So, this car is good enough for me approx. 95% of the days in a year. Which basically makes it totally useless to me.

Unless we have a step in battery and magnet/conductor technology, the lecky car will prove to be just as sustainable as the internal combustion equivalent.

However, such a car will be pretty good in cities and congested areas, using next to no energy when moving at slow speeds, even regenerating the kinetic energy when braking.

At least the lecky car will be a doddle to maintain, short of the user electrocuting themselves.

The real problem is that national adoption of such cars will lead to our governments introducing heavy national congestion charging, what with the loss of all that lovely fuel duty. Ultimate financial saving to the end user – none!

Still, it might end much world conflict…..might……

Solar panels produce about 125 watts per square metre in full sun (about 1/3rd of that in light cloud);

Cost about £500 /M sq

Weigh about 10Kg /M sq

A very modest electric 'engine' would use 15,000 watts (20 hp)

so if you cover a car with solar panels you might be able to drive as much as 30 mins / day

>As I see it, the simple answer is plug-in hybrid cars

the answer to what?

* Electric cars are / must be more polluting than the equivalent fossil fuelled car!

and btw all those fossil fuels came from plants that absorbed CO2 - did that locking up of CO2 cause global cooling?

AndyD 8-)#

"Contrary to what the oil companies and car companies tell us (not that they have vested interests), most diesel engines will run quite happily on vegetable oil with little or no alteration to either the oil or the engine."

Diesel appears to be the most efficient means of propelling cars for the forseeable future, and indeed if you can run on vegetable oil then the benefits outweigh even more strongly the disadvantage of smelling like a chippy. A big flaw in this plan is that the most modern diesel engines won't run on veggie oil at all, even with pre-heating as they use extremely high pressure fuel rails that will gunk up at the merest whiff of oil. I'm not sure they are warranted for use with bio-diesel either. Your best bet is to get a diesel from the 90s which pretty much all run OK on oil (providing it's got the right type of fuel pump).

http://www.veggiepower.org.uk/page208a.htm

I have a petrol car. It's a Citroen C2 which has 2 doors, four seats and a boot the size of a very large shoebox. It's absolutely fine for what we do most of the time - the odd drive to the other end of the country, running our baby to hospital, driving to work etc. What it's really rubbish at is taking, eg, a bath, to london, to use a recent example. It's not too clever off road either.

So what do we do when we find our nice, cheap to run car is unsuitable for the task in hand? We ask a mate, or if it comes to it, hire one. Same applies if your sports car isn't suitable for going long distances but otherwise meets your needs (and next time you meet someone with a Lamborghini, ask them how often they drive >200 miles).

The thing that the environmentelists choose to ignore is that electric and hydrogen powered cars may not themselves pollute, but the electricity and hydrogen production process pollutes.

As we all know, to make electricity, you have to burn coal or natural gas or have a "dangerous" nuke power plant. All of which are hated by the non-pollution crowd.

Anyone know of any way to make hydrogen that doesnt use electricity?

Bottom line: electric and hydrogen powered cars still pollute

"WKTEC" opened my eyes. Take the FUD around battery life. Drivers of the California EVs liked batteries - they actually liked the freedom of charging up at home or at work. (How many of us actually enjoy the experience of filling up at a petrol station? Contrast this with mobile phones - no-one complains because we have to charge them. Its all down to conditioning)

The annual service was just a change of brake and washer fluids. No oil, no oily mechanics. EVs have the potential to be very, very disruptive.

Sure, there's still things needed before they can be as cheap as a compact town car, but there's still lots of scope. But don't worry - the mainstream US car industry isn't going there in a hurry as they just haven't "got it" and are financially crippled. The cars offered to the California EV program were disgusting, as if built for people that wanted to be punished. Nor have the UK 'leaders' got it (apart from a few, well done Lotus).

I'm disappointed to see comments on a technologically-savvy site here from folks who don't got the vision either. But then again, how many of us envisaged what an internet-enabled society would mean 10-15 years ago?

The ICE isn't the only technology to vanish over the horizon of obsolescence. The steam engine, the 8-track, and aqueducts all came and went. During their peak, few could imagine their demise. But once the tide turned, change came quickly. The tide against the ICE is their poor energy efficiency, their regular need for complex repairs, their inability to connect with solar/wind power, and the expense of the fuel itself. Not only will electric cars cost less, but their fuel will cost less and their repairs will cost less. Bye Bye, ICE.

While it's true that battery electric vehicles (BEVs) produced now would most likely draw their energy from polluting sources, the idea is that they don't have to.

Car powered by regular engines are forced to burn hydocarbons and are always thus going to be air polluters.

However, BEVs will most likely in the future derive much of their energy from renewables, and the rest will be from efficient non-renewable sources. This energy source is a lot cleaner than petrol, diesel or bio-fuels.

Several people have commented that electric cars are net polluters, as they simply transfer the pollution upstream to the electrical generator. The implication is that petrol powered cars aren't so bad after all. The alternatives offered are biofuels and hydrogen. This analysis suffers from these problems:

1) Refining petrol takes electricity, too. The last I heard, the amount of electricity used to refine a gallon (or liter) of petrol is roughly equivalent to the electricity that would be used to cover the distance that gallon would take you. In effect, petrol production puts out pollution twice -- once in the refining, and once in the burning.

2) Electric cars approach something like 3 times the efficiency of petrol cars. Even if you assumed electrical generation from the worst of sources -- 1950's-style coal-fired plants -- the net pollution from electricity would be far less than petrol.

3) Electricity can be generated from just about any difference in potential energy. This means electricity has more possible sources -- a good many of them pollution free -- while petrol has only a few, all of which pollute.

4) Biofuels have promise, but they also promise to conflict with our food supply. In the best possible cases, the amount of land necessary to provide adequate biofuel is considerable; in the worst, unworkable.

5) Hydrogen is probably unworkable. It must be manufactured -- often using lots of electricity -- and consumed quickly, as it doesn't store well. It also seems to deliver roughly half the efficiency of petrol for a higher cost. I believe it will only be viable if we develop extraordinarily cheap electricity production mechanisms (fusion?).

I believe the biggest shortcoming of electric cars, with current technology, is that we aren't used to them. The practical problems (like where to charge if you park on the street) will be solved pretty easily once there are enough electrics on the road. In a very few short years, batteries will be good enough to carry a car some 500 miles between charges, and 1,000 mile batteries are foreseeable. Pair this range with the enhanced performance and improved reliability electrics offer, and I can't see a long future for petrol.

The ignorance displayed in the above report and most comments is stunning. Don't people feel any need for research or factual citations before they start shooting off their mouths?

I have a guest blog on EVworld as 'EVolution,' that cites studies showing, among other things, that electric vehicles, or EVs (including coal-fired fuel-making,) reduce pollution by at least 95% from levels caused by internal combustion vehicles (and their fuel-making, the production of petrol.)

http://www.evworld.com/blogs/index.cfm?page=blogentry&authorid=83&blogid=223&archive=0

EVs are still in development; we haven't yet seen the EV equivalent of the Ford Model T. The Model T, by the way, broke down every few dozen miles, only went a hundred miles on a tank of petrol (which had to be sought out at feed and general stores, there being no fueling infrastructure,) and had to be backed up hills.

Every argument put forward to show that EVs are not practical went double for the Model T; I guess the buggy-whip makers' arguments against Mr. Ford's threatening new vehicle technology were as unconvincing as those of today's EV-bashers.

... the first electric car finishes in the top ten - no, twenty, to be fair - of a proper motorsport event - rally, race, whatever. Alternatively, I'll be seriously impressed when an electric vehicle can replace a petrol/diesel commercial vehicle in like-for-like work (NOT milk-floats!). Until that day, I'm ICE through and through.

After reading the above thread I'm disappointed that nobody has raised the weight question (or have I missed a post?). Why on earth would anyone need a 1000 + kg (thats kilograms, you convert at your discretion to whatever units you please) to transport an average of 120 kg (1.5 persons with some luggage) for commuting. More intelligent designs than the Tesla and likes will not come from a blindfolded conventional car industry however. We need re-inventors if not for the wheel so at least for useful and adapted individual transport systems. I don't care if it's compressed air, electricity or cow dung ...

There is another technology you have missed in your assesment of alternative fuels/energy transmission. Compressed air can be used as an energy storage medium in place of batteries. This has many advantages.

Carbon fibre air tanks are much cheaper than batteries.

Air tanks can be re-filled millions of times without loss of performance. This also means the tank exchange stations idea is more feasable than battery exchange. (would you exchange your £30,000 battery rig for an older one with less performance just because it's charged) (infact, we already have an infastructure for safely exchanging empty for full compressed gas tanks [butane/propane])

No rare metals or chemicals needed in production (the dependancy on lithium producing countries is a very big problem in the electric car dream)

Pretty safe. Spillage not toxic, not flamable. Although compressed gas can cause an explosion due to the rate of expansion upon rupturing a tank, we have many decades experiance handling it safely. There are many designs to allow a bottle to rupture safely inside a holder without any casing being ejected (even at 15,000psi)

Green energy production systems like wind and wave power can be setup to compress air directly instead of generating electricity to then run a compressor. This is actually cheaper than building electricity producing wind turbines and rellies less on copper etc.

The engine is farely simple and can be scaled to all aplications we currently use ICE for. You can even have one on each wheel. Re-generative breaking is a doddle. Even car cooling can be run by taking the cooling effect of the expanding air.

There are some issues that need to be worked on, but if a developer threw some money at the idea it's nothing that can't be solved easily. EG

No heating, electrics for lights etc - this could be solved with an air genorator or by using electric brake energy reclaim into batteries instead of air. Or you can even use the cold from the expansion to work a heat engine to make electricity.

The demo cars I have seen on te interweb are not very powerful - add more tanks, higher pressure, more cylinders in engine

Fast charging causes heat - Exchange stations and overnight charge remove this problem, slow charge much more efficient. Or fast charge heat could be used to heat buildings.

Just thought I best keep you informed of all the options!

The PFY

Lewis is surely wrong about the Electric Car, for the following reasons:-

A company called Eestor has recently made infrequent and quiet but highly encouraging noises about their ultracapacitor electricity storage unit. They expect to ship a small unit in production quantities this year (2007) but are expected to scale this up to deliver around 50 KW Hours in a unit weighing approx 150-200 Kg and a charging time of 4-6 minutes. That compares with the Tesla Roadster Lithium Ion battery at 50 KW Hours, approx 450 Kg and a charging time of 4-6 hours.

Three of these ultracapacitor units wired in parallel would deliver a range of around 750 miles between recharges and a recharge time of 4-6 minutes (assuming you just charge at 3 times the charge current for the smaller units). All that with a possibility of 0-60 time of 4 seconds (as the weight is similar - 450-600kg), though this depends on the size of the electric motor.

Now who in their right mind would want to drive 750 miles in a day without even a 6 minute break for a refill? Clearly there is a miles per recharge threshold somewhere between 250 and 750 miles per recharge which tips the balance in favour of the electric car. What is it Lewis? How much does battery technology have to improve for you to believe in electric cars?

And the fuel costs would be around 2 UK pence or 4 USA cents per mile for an electric car compared with around 10+ UK pence or 20 USA cents per mile for the most efficient hybrid petrol cars, or perhaps 20+ UK pence or 40 USA cents for a performance petrol sports car achieving 0-60 in less than 5 seconds. (Prices are for UK electricity and petrol).

A factor of at least two improvement in cost per mile comes from a "well to wheels" efficiency doubling for electric cars compared with the best hybrid petrol cars. This means that if you fed the power station with crude oil using the most efficient of today's electricity generation equipment you would get twice as many miles out of a given quantity of oil in an electric car at the far end than if you refine it and power the car with petrol. The rest of the price difference seems to be due to the different tax rates on electricity and petrol.

Given the recent EEC commissioner interest in the speed limits on German autobahns, it seems likely that there will be no public roads within the EEC where you can go faster than 80 mph (130 kph). The fact is that electric motors can deliver much better torque at lower speeds than petrol engines. If you double the capacity of an electric motor you can accelerate twice as fast without significant reduction in efficiency. If you do the same with a petrol engine you probably get around half the number of miles per gallon. If it is important to the driver to do 190 mph as well as 0-60 in 4 seconds then you can design the car with a bigger electric motor.

The above facts will be enough to influence the most ardent road hog who cares nothing for the environment in favour of buying an electric car once the price is right - and in 6 years it ought to be cheaper to make than a petrol car. The maintenance costs will be much less too.

Of course Eestor may not deliver the spec, though the internet gossip is encouraging. If they are just a year late then we will to excuse them as their power storage unit will still be a game changer. Even if they fail completely then a 17% annual improvement in Lithium Ion battery technology will produce a three times battery energy to weight ratio improvement in 6 years with the same result.

Personally I reckon 500 miles between charges removes the problem of range for all practical purposes. A 17% annual improvement in batteries over 4 years or a 10% improvement over 6 years will deliver this. Is Lewis really going to bet against a 10% annual improvement with all the investment from the laptop makers?

Either way, electric power storage in batteries or ultracapacitors is going to tip the balance for a significant proportion of car buyers in favour of electric cars and my best guess is that this will happen around the time of the London Olympics (2012), possibly with the aid of a little government financial inducement.

Lewis does not even seem to have heard of Eestor or done any sums for himself. Why not, I ask? Perhaps he will answer this.

If a driver also happens to care about the environment then an added factor is that the CO2 emissions of a performance electric car are about 25% of the most efficient of today's hybrid petrol cars. This is because power stations on average generate electricity from fuels which produce half the CO2 for a given energy output. With capital investment you can also remove the CO2 from fossil fuel power station exhaust and reduce this still further (to end up close to zero) or use renewables such as wind or solar - or even nuclear (but only if you happen to be French).

Finally, what about ethanol or hydrogen? Well, it turns out that the efficiency of producing these from whatever source is very significantly worse than using the source fuel to generate electricity, pump it through the grid, store it in a battery and use it to drive an electric motor in a car. The maths can be found in a white paper on the Tesla Motors web site at www.teslamotors.com/display_data/21stCentElectricCar.pdf. Clearly Tesla have an axe to grind, but the maths do look plausible to me.