Motoring: Where there's fire without smoke

The Japanese hybrid Prius is the best option for pollution-free motoring, says James Rupper

I'm a lapsed member of the Battery Vehicle Society, and it is not hard to find out why. Although it is a worthy aim to find an environmentally clean way to power your next car, battery technology just isn't up to speed at the moment. Range is limited, the batteries are heavy, and although charging them may be a simple process, finding somewhere to plug in when you roll to a halt on the M25 is going to be difficult. So until the technology can offer the performance, range and practicality of a petrol engine, electric power will be as dead as a flat battery.

However, Toyota think they may have come up with a solution by combining a conventional petrol engine with a silent electric one. They have given this working car a name, Prius, and put it on sale, but only in Japan.

The Prius manages to achieve twice the fuel efficiency of conventional petrol-engined cars, offering at least 1,000 kilometres from a tankful of petrol. It also cuts HC, CO and NOx emissions on the road to a tenth of those allowed under stringent Japanese regulations.

How does it work? Well, squeezed under the bonnet is a light, efficient and low-revving 1.5 litre petrol engine. That is joined to a gear train that acts as a clever automatic transmission. Finally an electric motor and generator fits on the other end to complete the hybrid package.

The key to the mechanical efficiency of this system is the electronic control of power to ensure that energy is conserved. The engine runs at an optimum 4,000 revs per minute and its main function is to drive the wheels, but any excess output is used to recharge the batteries.

The batteries are also recharged by regenerative braking: when the brakes are applied the energy from the wheels is transferred to the batteries. In turn, the batteries supply extra power via the electric motor when required for ascending a hill, or overtaking. In situations where the engine cannot run efficiently, or produces high emissions, for instance when the car is at a standstill in traffic, then it is switched off altogether.

So what is it like in practice? Impressive. The Prius is just like a conventional car, but quieter. In the cabin you turn the key and hear nothing so harsh as a rumbling engine, or even the hum of an electric motor.

The Prius is definitely a car you can live with, though the brakes are fierce and the steering too light, a combination of the regenerative brakes and Japanese specification. It is at home in an urban and light commuter setting, but coped competently on the motorway with equivalent performance to a Toyota Corolla 1.6 automatic, (100mph top speed) but greater frugality, with the potential of more than 70 miles per gallon.

The interior is roomy, especially for rear seat passengers. The dashboard is interesting with mainly digital instrumentation and a video screen display that works the stereo and a satellite navigation system, and even shows you which motors are supplying the power. Despite there being a battery pack positioned behind the rear seats, the boot is usefully deep.

Hybrid cars have been talked about for too long. Prototypes have been quietly forgotten about. Not only does the Prius styling look good but the package is sensible, and the hybrid power route means that nationwide outdoor three-pin plugs are not required. However, Battery Vehicle Society purists might question the value of having two motors and the use of air- conditioning.

For the moment the Prius is the best and only alternative the Japanese have got. There is a three-month waiting list, and I was told by a spokesman to expect an announcement soon. Toyota certainly wouldn't go to all the trouble of flying half a dozen cars over just to show off.

In Japan it sells for the equivalent of pounds 10,000, and Toyota are rumoured to be subsidising each car to the tune of pounds 20,000. It is unlikely to sell for anything near pounds 10,000 in Britain.

Prius may not be the answer to environment-friendly motoring, but it is a start. In the meantime I'm going to start the Hybrid Vehicle Society. Anyone else want to join?