BMW 7-Series

But away from the glitz of the exhibition, the firm is reported to be working hard to get one of California's most famous residents behind the wheel. Governor Arnold Schwarzenegger has already been offered a test drive, and it's hoped he'll take delivery of one early next year.

The BMW Hydrogen 7 is based on the existing 7-Series and comes equipped with an engine capable of running on liquid hydrogen or petrol. In hydrogen mode the car emits nothing more than water vapour. Powered by a 260hp 12-cylinder engine, the Hydrogen 7 accelerates from zero to 62mph in 9.5 seconds before going on to an electronically limited 143mph top speed.