The car hits the market next April and will be shown at the Los Angeles car show in November, the company said. It had said in March the hydrogen cars would arrive within two years.

A spokesman said the car would be leased to selected customers rather than sold because of its high price. Leasing rates would be similar to those for a top-end BMW 760LI with a full-service package.

The BMW 7 Series Hydrogen 7 Saloon is powered by a 260 hp twelve-cylinder engine and accelerates from 0-100 km/h (62 mph) in 9.5 seconds. Top speed is limited electronically to 230 km/h.

BMW has said it intends to build a few hundred such cars at first. They will be able to switch between burning standard petrol and hydrogen so that drivers will not be left stranded while the infrastructure to deliver hydrogen is built up.

"The integration of hydrogen drive in an existing vehicle concept which has already proven its merits in the market paves the way for an alternative to conventional drive concepts fully accepted in the market and with all the assets the customer is looking for in practice," BMW said.

The space that two fuel tanks take up means only the 7-Series will offer the hydrogen package at first. BMW's long-term goal is to offer hydrogen motors in all its cars.

BMW unveiled the world's fastest hydrogen-powered car at the 2004 Paris auto show. Dubbed the H2R, it can exceed 300 kilometres (185 miles) per hour and reaches 100 km per hour from a standing start in around six seconds.