I have seen the future and it’s straight out of a 20-year-old science fiction film. Remember the DeLorean in Back to the Future fitted with its own reactor called Mr Fusion? Well, the DeLorean has been superseded by a Mercedes A-class powered by an electrochemical reactor.

The technology is not brand spanking new. Scientists have been messing about with hydrogen fuel cells for a while. The difference is that DaimlerChrysler (which owns Mercedes) has managed to make the technology much more portable and compact. It fits under the car’s floor, leaving a normal-sized cabin.

The car does 0-62mph in a respectable 13.4sec, has a top speed of 100mph and comes with satellite navigation, air-conditioning and a CD player. The only emission from the exhaust is water vapour.

It’s not going to win any races and, like the first fax machine or home computer, is unrefined. But in less than the decade it took for mobile phones to shrink from field telephone size to chocolate bar size it could be in the showrooms.

The Merc runs on compressed hydrogen and has a valve where the filler cap would normally be. There are no filling stations yet — except one in Essex used for a fleet of trial buses — but BP wants eventually to sell hydrogen on motorways. Honda in America is already piloting home energy stations which make hydrogen from natural gas so you can refuel your car in your drive.

The Mercedes starts with a whine like a miniature jet fighter. It takes 8 to 15 seconds, depending on the air temperature, to power up. It’s a bit like waiting for a computer to boot up, so aside from the fact that it has “F-Cell” emblazoned across it in big purple letters it wouldn’t make an ideal getaway car.

A needle on the dashboard flicks to “Power max” and the car is ready to go. The gearbox is single ratio with park, neutral, reverse and drive. The 65kW electric motor fuelled by the hydrogen cells generates about 87hp, and you get a flat torque curve. In “sport” mode it moves off with a jolt but it also has a “comfort” setting that softens the acceleration for slippery conditions.

Because power is instantly on tap the car is good for stop-start city driving. And the most noteworthy thing is that it’s completely normal. It’s not a Tomorrow’s World contraption that conks out in the studio. It’s here and it works.

There are two drawbacks. First, its range is only about 93 miles. The two kilograms of hydrogen in the tank has the energy equivalent of about 7-8 litres of diesel. Second, if the temperature drops below zero it won’t start because the hydrogen-oxygen reaction fails.

DaimlerChrysler reckons it has solutions to both problems. It’s working with its suppliers to make the car less sensitive to the cold. And it’s planning a new fuel tank that will give a 250 mile range. Future versions of the car could include batteries that can be recharged from mains electricity.

Using compressed hydrogen poses technical challenges. The pressure in the extended-range tank would be about 700 bar (an average car tyre is only about 2 bar). DaimlerChrysler denies there are any safety implications. The aluminium and carbon fibre tanks are built to withstand collisions, but even if one is ruptured the hydrogen would simply leak out, the company says. In this event, detectors would shut down electrical systems to reduce the risk of the hydrogen igniting.

But won’t people remember the Hindenburg? Ah yes, but that was because the hull of the airship was flammable, DaimlerChrysler says, not because the craft was hydrogen-powered.

The car maker has built a small fleet of A-class demonstrators — you can’t yet buy one — and it’s working on a more powerful version of the system for a Mercedes B-class. It reckons it has already spent €1 billion (about £678m) on development, a huge vote of confidence in the technology. It also owns 20% of Ballard, the company that supplies the fuel stacks. Ford owns another 20%. The two giants have put aside their differences and have decided that as oil runs out, fuel cells are the way forward.

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