(Tue 02 Mar 10)

Two concept cars at the Geneva Show demonstrate Audi's thinking about partly or fully electric cars. One is a hybrid - like most cars at Geneva this year, or so it seems - and it's based on the A8.

Presented as a "technical concept" rather than a production-ready vehicle, it uses both an electric motor and the familiar 2.0 TSI turbo petrol engine. With a combined maximum output of 253bhp, these gives the A8 hybrid a top speed of 146mph and a 0-62mph time of 7.6 seconds, along with CO2 emissions of 144g/km.

The A8 can reach 40mph using either the motor and the engine or just the motor. Above 40mph the engine takes over full duties, leaving the motor to act as a generator for the lithium-ion battery pack.

There are no immediate plans to put this car into production, but the technology is similar to that which will be used in a hybrid version of the Q5 SUV, due to be launched later this year.

Also on the Audi stand is the latest e-tron concept. Unlike previous e-trons, which bore a close resemblance to the R8 sports car, this one is based on the new A1. It's driven permanently by an electric motor which has a maximum output of 101bhp, leading to a 0-62mph time of 10.2 seconds and a top speed on the high side of 80mph.

In city traffic, the A1 e-tron's range is just over 30 miles, but that can be extended by a further 120 miles or so thanks to a small petrol rotary engine which acts as a range extender. Fuel consumption figures for cars with this set-up are difficult to calculate, but according to a draft standard for this sort of thing the Audi should be able to manage 148.7mpg and emit CO2 at the rate of 45g/km.

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