A fleet of 32 Hyundai Tucson and Kia Sportage 4x4s will be handed over to the University of California and the US Army to be put through hot- and cold-weather testing in California and Michigan.

Fuel-cell vehicles are claimed to be the cars for a greener world because water vapour is their only emission, although Hyundai and Kia believe their widespread availability is likely to be at least 20 years away.

They are fuelled by hydrogen, which is used to create electricity to power a motor. Kia claims the fuel-cell Sportage can achieve fuel economy equivalent to around 67mpg with a petrol car.

The Koreans claim to have solved many of the problems associated with fuel-cell cars, such as poor cold-weather starting, short cell life and unreliability.

Kia is convinced it will be in a position to sell 10,000 fuel-cell Sportages a year by 2010, though it admits the buyers are likely to be organisations with their own hydrogen supply until refuelling points become commonplace.