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.