Imagine never having to refill your car with petrol, or almost never. The idea has inspired myriad designs that never moved beyond the drawing board. It has induced the automotive industry to invest billions in prototypes and even production models that have looked good and driven well, but never far enough or at a price that most motorists could stomach.

The post-petrol car is the holy grail of green automotive design. Unlike the grail, it may yet be found.

On a closed test track northwest of Detroit, 700 General Motors engineers and support staff are hoping to defy the company's eco-villain image as producer of some of the least fuel-efficient vehicles on the planet, including the egregious Hummer, by producing the world's first truly practical and affordable plug-in electric car.

The Chevrolet Volt, unveiled this month, contains no revolutionary technology but is a revolutionary concept. It promises to solve, in one car, the problems of the chronically short range of all-battery cars and of stubbornly high carbon emissions in even the most efficient hybrids. Other manufacturers are working towards the same goal, but none is as close to achieving it.

GM could fail. Its rivals - and, perversely, many of its longstanding critics in the environmental movement - would like it to. But success would save the company's reputation and, potentially, its bottom line. It could also kick-start a process leading to the historic decoupling of America's car culture from costly and environmentally ruinous oil. GM's chairman acknowledges the scale of the gamble; he has frequently invoked President Kennedy's challenge to the US to put men on the Moon by 1969. But this is precisely the sort of gamble that the titans of Western industry must learn to take if climate change is to be tackled without drastic curbs on both the fruits and engines of prosperity.

The Volt works by using state-of-the-art batteries and an electric motor to give it a range of up to 40 miles without recharging or using petrol. Like hybrids such as the Toyota Prius, it also has a petrol engine. Unlike hybrids, it uses that engine solely to recharge its batteries on longer journeys. But since their 40-mile range (roughly five times longer than that of a Prius running on batteries alone) covers the average daily drives of 80 per cent of Americans, and since the car is meant to recharge overnight from a normal mains socket, most Volt users would almost never have to fill their tanks.

Mains electricity must come from somewhere. But the more that Western economies switch to nuclear generation, and to carbon sequestration of the kind that the Government required this week for future British coal-fired stations, the cleaner plug-in cars will be.

There is a hitch: GM has yet to perfect its battery packs and will have to charge up to £20,000 for its new cars. But it has given itself a deadline of 2010 by which to bring them to the market, and its competitors are racing to beat it there. In a recent paper for the Royal Society, Stephen Schneider, of Stanford University, called for a “learning-by-doing feeding frenzy” in which Public Private Partnerships would fashion incentives to help humanity to invent its way out of dependence on dirty old technologies. Not before time, that frenzy has begun.