(Thu 25 Feb 10)

One of the most technically fascinating cars at next week's Geneva Show will be a hybrid version of the Lotus Evora.

Most hybrids, and certainly all those currently in production, have a conventional engine which is supplemented (and on occasions replaced) by an electric motor. The Lotus system is quite different. The Evora has two electric motors, one driving each rear wheel, with a total power output of 408bhp, giving the car a 0-60mph time of around four seconds.

They do all the real work. The engine is a very light and compact 47bhp 1.2-litre petrol unit which was revealed in September last year and is a key part of the remarkably fast and economical XJ-based Jaguar Limo-Green prototype. It's known as the Range Extender because its role is largely to keep the battery pack topped up. It doesn't actually drive the car, but it does mean the Evora can keep going well beyond the 35 miles that are all it would manage on a single charge.

Each motor can apply up to 204bhp to the wheel it's attached to, but they don't necessarily provide the same amount of power at the same time. The balance can be altered automatically to provide something similar to rear-wheel steering in tight situations, or to maintain stability at high speeds.

There is, of course, no gearbox, but Lotus has added something that feels rather like one. Operated by paddleshifts, it increases driver interaction with the car, though its actual effect is to change the driving characteristics. One example is that the driver can get the effect of engine braking by shifting down through the "gears"; what is really happening here is that the regenerative effect of the motors is being increased.

The "gearbox" is also linked to an internal sound generator which makes the Evora seem to have a high-performance engine even though it actually doesn't. Virtual engine noise is also played through speakers at the front and rear of the car so that pedestrians are able to hear that it's coming.

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