Original URL: http://www.theregister.co.uk/2012/10/29/review_toyota_prius_plug_in_hybrid_car/

Toyota Prius Plug-in Hybrid car review

A huge leap forward for the world's most popular hybrid

By Alun Taylor

Posted in Science, 29th October 2012 08:00 GMT

Extended electric-only driving range has been a long time coming to hybrid cars but with the arrival of the Vauxhall Ampera and now Toyota’s Prius Plug-in the breed may finally shake off the reputation of vehicles that only exist because Americans don’t like diesels.

Toyota Prius Plug-in Hybrid car

The mains attraction: Toyota's Prius Plug-in Hybrid

In a nutshell what we have here is a Toyota Prius with a larger battery pack that extends the electric-only range from just over one mile at speeds below 31mph to more than 15 miles at up to 51mph. Realistically, those 15 miles could cover typical daily tootling around for urbanites.

If you need more range, as suggested by the name, charging the traction battery can now be done from a power socket as well as from regenerative braking and the petrol engine. Mechanically the plug-in Prius is near enough identical to the standard car. Under the bonnet is a 98bhp (73kW) 1.8L Atkinson cycle VVT-i petrol engine mated to a CVT gearbox and a 60Kw (80bhp) electric motor.

Toyota Prius Plug-in Hybrid car

Note the charge socket cover – petrol goes in the other side

It’s the type of battery that has changed. Out goes the 1.31kWh nickel-metal hydride pack and in its place is a 56-cell 4.4kWh lithium-ion unit. The new battery is 38kg heavier, a significant portion of the car’s 55kg overall weight increase. It's bigger too but you only lose 3 litres of luggage space.

Charging the battery is a simple matter of grabbing the cable out of the boot cubby and plugging it into a wall socket. A full charge never took longer than 2 hours and worked perfectly well using the 13amp 3-pin socket in my hallway and an extension cable.

Toyota Prius Plug-in Hybrid car

Warning: charge points like this are still rather scarce

There’s a practical consideration here too: As it can be charged in such a short time, I could juice it up without leaving it plugged in overnight and risking someone stealing the charge cable. Toyota recommends using a custom socket in a wall box and has partnered with British Gas to instal them and specifically advises against using extension cables but as I say, it worked just fine for me.

Cabin cruise

The only clues in the cabin to the increased electric range are the Eco, HV/EV and City EV buttons that sit in the same place as the Power, Eco and EV buttons on the standard model. On the exterior, some very subtle styling changes and new badges aside, it’s only the cover for the charge socket with its plug emblem that gives the game away.

Toyota Prius Plug-in Hybrid car

EV or Hybrid? Take your pick

Assuming the battery has enough charge, at any time the HV/EV button lets you cycle between Hybrid and Electric vehicle modes. In the former, the Plug-in Prius behaves much like the standard car, albeit one that’s been at the steroids with the electric motor assisting the petrol engine and allowing for some limited electric-only running. In EV mode the new Prius drives much like a Nissan Leaf or Vauxhall Ampera with ample electric poke available to keep up with urban and suburban traffic.

On the road, I found that EV mode could be pushed to 59mph before the petrol engine fired up, 8mph better than Toyota's claim. The range prediction was bang on though. On three successive full-charge runs the car fell out of EV mode after 15.1, 14.6 and 16.2 miles. If you charge the battery from the mains and then drive off in hybrid mode, the indicated EV capacity is held in reserve until activated. This means you can charge up at home, drive to your destination and then engage EV mode when you get there.

Toyota Prius Plug-in Hybrid car

Battery at the back but drive at the front

Indeed, that’s exactly what I did on a trip to Wakefield. I held off the EV charge until I reached the outskirts of the town centre. I then engaged City EV mode whilst driving around town, nearly running a few of the locals over in the Trinity Walk car park, due to my silent approach. With City EV, you can accelerate more aggressively for short periods too. For instance, pulling away from traffic lights without the petrol engine firing up. Otherwise it’s the same as EV mode, however, the electric motor does have to be up to temperature before you can select it.

Toyota Prius Plug-in Hybrid car

Power monitor

The Eco setting smoothes out the throttle response and dials back the air conditioning – all in the name of eking an extra mile or two from each gallon or kWh – and operates in EV, City EV and Hybrid modes. I suspect most drivers will leave their Plug-in in Eco unless in an almighty hurry or driving in the tropics. Once the EV charge from the mains is exhausted, theoretically, it can be replenished by the engine and regenerative brakes but, in my experience, only by a small amount. A 20 mile run added just over a mile to the indicated EV range, so any meaningful contribution would require a long and preferably downhill journey.

Toyota Prius Plug-in Hybrid car

EV system indicator

To help the driver make sense of all this EV/HV malarkey, the battery power indicator has two forms – a solid graphic showing the EV charge and then a segmented graphic showing hybrid charge. As soon as the EV battery graphic hits empty, it swaps to the hybrid battery graphic showing full. Even in hybrid mode though you will get more electric-only driving out of the Plug-in than the regular Prius, owing to its beefier lithium-ion battery. The best I managed in hybrid mode was 4 miles at speeds up to 40mph, significantly further and faster than the standard car is capable of.

Inside the Prius – in pictures

Toyota Prius Plug-in Hybrid car

Power battles

Toyota Prius Plug-in Hybrid car

Bit too much plastic for a 30 grand motor

Toyota Prius Plug-in Hybrid car

Interior is spacious and the same as the basic Prius

Toyota Prius Plug-in Hybrid car

Place to hide the Vince

Toyota Prius Plug-in Hybrid car

Label to remind you its a plug-in hybrid

Toyota Prius Plug-in Hybrid car

Plug 'n' stay

Government approval

The Plug-in also feels a faster car. The electric motor may be no more powerful and headline performance similar (0-60 in 11.4 seconds and a top speed of 112mph) but given there is invariably more juice available, the electric motor can lend its 207Nm shoulder to the wheel more often and for longer. Also, when you put your foot down in the Prius Plug-in to overtake, you still accelerate more strongly than the standard car, even though the engine doesn’t rev as hard. This makes for an altogether more enjoyable and rapid motoring experience.

Toyota Prius Plug-in Hybrid car

Tailgate design good for drag, less so for visibility

How does all this equate to economy and CO2 emissions? Officially the Plug-in returns 134.5mph and emits 49g/km in plug-in mode and 76.4mpg and 85g/km in hybrid mode. The first figure is effectively meaningless as it depends entirely on how many miles more than the EV range you cover between charges. In hybrid mode, I found I was averaging over 60mpg. Given its 9.9 gallon fuel tank, the Prius can cover more than 600 miles between fill-ups and charges, significantly further than the Vauxhall Ampera with its 7.7 gallon capacity.

There is a premium to pay for all this extended electric range goodness though. While the basic Prius will set you back from £21,600 the Plug-in costs £32,895. However, it does qualify for the £5,000 government e-car grant and comes with a host of extras including the touch screen Toyota Touch & Go navigation system, a very nice eight-speaker low power JBL stereo and parking cameras.

Toyota Prius Plug-in Hybrid car

The front end is a little different to basic Prius, but you'd never notice

Take all that into consideration and you are paying around £4000 more for the lithium-ion battery which, in my book, makes it the clear choice if you are in the market for a hybrid of any sort. Despite the lower EV range, I’d take the Plug-in Prius over the Ampera because it feels like a more accomplished engineering approach to extended-range EV motoring. It’s cheaper too.

Verdict

RH Recommended Medal

If current hybrids leave you with the feeling that, as an engineering concept, they are a bit half-baked, the new Prius Plug-in could be the car for you. The much increased electric-only driving range and improved electric hybrid assistance have turned the Prius into the car I have always thought it should be and, indeed, wanted it to be. Colour me impressed. ®

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