A new generation of vehicles which are 99 per cent cleaner than cars of 30 years ago have been on display at the San Jose Auto Show in California.

The significant reduction in emissions has been achieved through a process involving cleaning the fuel entering the vehicle, burning the fuel more precisely in the engine, and removing undesirable emissions with a catalyst.

The vehicles have been designed in accordance with the US Environmental Protection Agency's new guidelines on emissions, which include subjecting all light vehicles to the same emission standards as cars and treating vehicles and the fuels they use as one integrated system.

The Alliance of Automobile Manufacturers' president and chief executive Fred Webber, who has helped stage the show, said that the event represented just how far the industry had come.

"The San Jose auto show has the cleanest vehicles ever," he commented.

"These aren't just concept cars that might be available in the future. We're talking about ultra-clean vehicles that are for sale on dealer lots everywhere right now."

The San Jose Auto Show runs from the 5th to the 9th of January and offers a close-up look at the future of automotive design and the latest technological advancements, including sneak peeks at futuristic "concept cars".

Members of the Alliance of Automobile Manufacturers include all the major automotive firms, with DaimlerChrysler, Ford, General Motors and Mitsubishi Motors all members.