| First Drive | | Toyota Prius Plug-in Hybrid |

Following the huge international success of the Prius, Toyota has developed a plug-in hybrid version. Yes, the existing car is already a hybrid, but this one allows you to plug into a charging point and juice it up to extend the amount of time that the car can travel on electric power alone.

It won't be on sale for another couple of years, but 20 examples will be up and running on London's streets as part of a three-year lease demonstration programme from July 2010. Toyota has agreed to spread the cars between some of its biggest existing business customers, including Sky and News International, publishers of The Sun and The Times. Other scheme partners are the Metropolitan Police, Transport for London and the Government Car and Despatch Agency.

In the Metal

You'd be hard pushed to differentiate the plug-in Prius from the existing car. It appears identical, the only exception being a small square cap - similar to a fuel filler cover - located just above the passenger side wheel arch. Flip it open and you'll find a plug socket for charging the battery, ideally placed for when you pull up next to a charging point.

It's the same deal inside, too. The space aged, sweeping dash layout from the standard Prius remains, as does the LCD screen mounted at the top of the dashboard. That tells you when the car is using electric or petrol power and how you’re doing as a green driver. The only physical changes of note are the fact that the boot floor is marginally higher, due to the larger, higher capacity battery. This also brings a 130kg weight gain.

What you get for your Money

Aside from the obvious yellow battery charging cable (usually stored in the boot) there are two unique features to the plug-in Prius. The first is the air conditioning system, which alters the temperature inside the car while the battery is charging, so you're not wasting energy warming up or cooling down the car on the move.

The second new feature is a rather twee screen on the dashboard display that indicates how much CO₂ you've saved by driving on electric power. It's displayed by the image of a growing forest.

Prices won't be confirmed for some time, but Toyota claims that its customers will pay around £300 to £400 per month to lease the car under the current scheme. That's not necessarily reflective of how much it will cost when full scale production begins, but it's all we have to go on for now.

Driving it

The significance of Toyota's PHV (Plug-in Hybrid Vehicle) technology is the use of a lithium-ion battery pack rather than a nickel-metal hydride item as used in the standard Prius. The lithium-ion battery is faster to recharge but two thirds of the battery pack must be charged by an external electricity supply. Toyota reckons that a full charge takes about an hour and a half from a standard socket.

In practice, this means that the Prius can run on electric power alone for much longer. The standard model will drive for only 1.2 miles before the petrol engine has to kick in, but the Prius PHV will plod on for 12.5 miles on electric power alone. That doesn't sound like an enormous amount, but Toyota assures us that it's enough to cater for the majority of commuters, particularly in London where the trials will take place. It's also enough to significantly slash fuel consumption and emissions: quoted figures of 108.6mpg and 59g/km are pretty groundbreaking.

As far as performance goes, the 1.8-litre four-cylinder petrol engine and electric motor combination will muster 134bhp in tandem and the Prius is good for 0-62mph in 13.7 seconds. It will also hit 112mph with both engine and motor working together, or 62mph on battery power alone. As with the exterior, it's difficult to notice any difference in the driving experience between this and the standard Prius, with the exception of the fact that it's difficult to get the engine to kick in during town driving. It's still eerily quiet and all the torque is available from zero revs, so it's usefully nippy in stodgy traffic.

Worth Noting

It's fair to say that the Prius PHV makes less sense to those with a long motorway commute, but if you live in the capital - and the current lack of electric car charging points is a worry - then fear not. We're promised charging points at tube stations by the end of this year and you should also see plenty springing up in supermarket car parks and other busy public spots. London Mayor Boris Johnson expects to have 25,000 of the things up and running by 2015, too.

London isn't the only city to be trialling the Prius PHV, as 100 examples are on test under a similar scheme in Strasbourg, France. The plug-in Prius has also made its way - albeit in smaller numbers - to Berlin, Warsaw, Helsinki, Stockholm, Lisbon, Madrid and Oslo.

Summary

Full-scale production is a way off yet, but if the forthcoming trials go well - and there's no reason why they shouldn't - then Toyota could be on to an even bigger winner with the Prius PHV. The emissions and fuel economy are incredibly impressive, and they'll be serious selling points. The clincher will be the price, as the PHV will no doubt be more expensive than the standard Prius and lithium-ion batteries don't come cheap. It's not confirmed, but the estimated on-sale date is early 2012, so if Toyota can wrap up its research and settle on an acceptable price by then, the Prius PHV could prove even more popular than the existing model.