Instapundit has linked to a story about a car that runs on compressed air. Check it out.
It's got a top speed of about 68 mph, which works for commuter driving in Europe and will hopefully work in India and China. It costs about $2 to fill up on air and then the car can run for at least 125 miles, or about 10 hours of driving time. It has double the range of electric cars and costs about 1/10th as much per mile as a gas-powered car (assuming European petrol prices). The air exhaust is cold enough to cool the car.
Heating would appear to be a problem, however.
Reminder number 246,376,276,456,876 that the way forward actually involves going forward. Backwards simply won't do. Who knows if this kind of thing will work, but I'm really glad that really smart people want to make fantastic fortunes solving problems.
(If anyone can explain why every triad of numbers above ends with a 6, you deserve to make a fantastic fortune as well).