The gas company BOC said the hydrogen-powered Ech2o car needed the input of 25W for a 25,000-mile global trip. This is the energy equivalent of less than two gallons of petrol. Emissions would consist of water. But with a top speed of 30mph, the journey would take more than a month, even if the car was driven flat out.

On Thursday, the Ech2o will make a shorter journey to try to break the world fuel efficiency record. Jack Dex, 13, of Southam College, Warwickshire, will drive the prototype at the Shell Eco Marathon at Rockingham Raceway, near Corby, Northamptonshire. Small and light, he is also an experienced go-kart driver.

Most Eco Marathon vehicles run on petrol or diesel, but the record, 5,385km/l (just over 15,000mpg) is held by a hydrogen-fuelled Swiss car.

BOC designed the hydrogen storage system for the Ech2o, OSCar Automotive designed the body, chassis and steering system, and the electric power train was developed by Oxford University.

The car is made of carbon fibre and aluminium.

The concept of hydrogen fuel cells was invented in 1839 by Sir William Grove.

BOC's director of sustainable energy, John Carolin, said: "The lessons from this and other projects will show that hydrogen fuel cell-powered vehicles could be a practical, attractive and a viable economic alternative to diesel- or petrol-fuelled vehicles."