Along with some Japanese and European makers, the US is developing hydrogen fuel cells that promise no tailpipe pollution at all (and no carbon dioxide). They seem to be making progress - though so far none of the car companies has made it clear how the hydrogen itself can be produced in a green way - eg by solar power. If introducing fuel cells simply means existing power stations working harder, pollution from the primary source will increase - and power stations produce more pollution than cars, anyway.
The car manufacturers' need to innovate conflicts with their need to keep current customers happy. No matter how censorious we Europeans get, Yanks want their cheap gasoline. They argue that inexpensive energy is one of the keys to the most successful economy on Earth. They also like driving around in pick-ups and 4x4s, and sedans with bonnets big enough to land aeroplanes on.
Sales of "light trucks" (Yankspeak for big 4x4s, pick-ups and MPVs), the most gas-guzzling sector of the market, are booming in the US. The biggest selling vehicle by a mile is the Ford F-series pick-up, and the biggest single growth area is in big off-roaders. And by big, I mean big. The Range Rover, mammoth of the motorways here, is a motoring minnow in the US 4x4 market.
So as long as the Americans want trucks (and by 2000, analysts reckon, light trucks will make up more than half the total vehicle market), the US makers will give them trucks. The Japanese, equally customer focused, are also jumping on to the truck gravy train. Lexus, in Europe a byword for tasteful discretion and efficient engineering, launched a new 4x4 in Detroit that was almost as big and thirsty as the local gluttons.
Meanwhile, to salve their consciences and those of the American people and their government (Bill Clinton even went on national TV to congratulate them), US car manufacturers are making bold noises about exciting new green technology.
Nonetheless, despite the PR puff, it is highly unlikely that we'll see any of these high-tech, potentially eco-friendly solutions in volume production for many years. The "production ready by 2004" boasts for hydrogen fuel cells may be true. But unless there is a huge change in American public opinion, and taxation, these cars cannot possibly hope to compete with gasoline cars on price or popularity. They will be no more than minority vehicles, run by state utilities and car company-backed bodies - useful test-beds for the day, a few decades in the future, when new technology will either be cheaper (as oil prices rise), essential (as oil runs out) or mandated by government.
Either way, the car industry is preparing itself for change. It doesn't expect it to happen quickly, and it's confident that there's life left in the old petrol internal combustion engine (rather more than many Detroit press conferences suggested, in fact). But in the meantime, hydrogen fuel cells and other new-tech powertrains keep the journalists busy and make the car companies look good.
One day, though, they'll have to deliver. And that's when the US car makers, still the world's biggest, will show their true colours.