General Motors needs to give a green light to heavy investment to develop a mass-market hydrogen-powered car within the next 18 months to ensure the US carmaker – struggling with a financial crisis – does not get left behind on clean vehicles.

But GM is under pressure from rivals led by DaimlerChrysler and Toyota, who plan to start selling fuel-cell cars by 2012 and 2015 respectively. Honda has begun putting fuel-cell test cars on the road in California.