In a stunning announcement at the opening of the Detroit motor show, Rick Wagoner, GM's chairman and chief executive, also said ethanol was an "important interim solution" to the world's demand for oil, until battery technology improved to give electric cars the same driving range as petrol-powered cars.


GM is working on an electric car, called the Volt, which is due in showrooms in 2010, but delays in suitable battery technology have slowed the project.

Mr Wagoner cited US Department of Energy figures which show the world is consuming roughly 1000 barrels of oil every second of the day, and yet demand for oil is likely to increase by 70 per cent over the next 20 years. Some experts believe the supply of oil peaked in 2006.

The remaining oil reserves are deeper below the Earth's surface and therefore more costly to mine and refine.

"There is no doubt demand for oil is outpacing supply at a rapid pace, and has been for some time now," Mr Wagoner said. "As a business necessity and an obligation to society we need to develop alternative sources of propulsion."