According to project leader Sachito Fujimoto, the Honda FCX has about the same power as a 2.4-litre petrol engine with a top speed of 160 km/h and an output of 95 kW/129 hp.

Roland Krueger, who is responsible for hydrogen research at Ford's research centre in Aachen, points out that the hydrogen-powered Ford Explorer easily keeps up with traffic flow with an output of 130 kW/177 hp and a top speed of 140 km/h.

In the prototypes, burning hydrogen and oxygen that produced the energy for an electric motor works well. The only emission is water vapour. But the dilemma faced by the project engineers is that "the space required by the components, their lifespan, the temperature factor, the range and the costs involved are still a problem," says Ford's Krueger.

The latest fuel cell generation has made headway on weight and space for most components. "Our system in the FCX has become 180 kg lighter and 40 per cent smaller," says Fujimoto.

Producers are also making progress with the problems faced by hydrogen-drive during huge temperature variations but there has been no real breakthrough in the technology.

Hydrogen-driven vehicles can be found in car fleets across the globe. But the engineers have continuously postponed a schedule for serial production. Ford's Krueger reckons that it will take at least two more car generations and believes that serial-production of the car will begin in 2015 at the earliest.

Mercedes-Benz research engineer Christian Mohrdieck expects a start in 2012.

Henner Lehne, an expert from the CSM prognosis institute in Frankfurt says, "the classic fuel cell will first have to prove itself in other sectors, for instance in the normal household, before it can go into mass production in the automobile."

"There is no otherway to finance the high development costs," he argues.