Staying power

* Beginning of end for petrol and diesel? * Vauxhall's electric car on sale by 2012 * Range of 310 miles and 176mpg...

Staying power

GM reckons the batteries will be good for 10 years or 150,000 miles of use, and can be fully recharged in three hours from a standard mains socket. You can even set a timer so they draw on the cheapest overnight electricity.

The battery packs are of a similar lithium-ion construction to those found in a laptop computer or mobile phone, but are based on different chemistry to avoid potential overheating problems, and have their own internal liquid cooling system.

GM has already had 30 pre-production cars running around to test the Voltec drive system, and will put 80 prototype cars on the road later this year to complete final development.