Yes, it's true. You can run a car on nothing but air, compressed air that is. Rather than burning gasoline to create the gases that drive a piston up and down (and provide motive to your motor), some automakers plan to use air compressed to around 4,500 pounds-per-square-inch instead. After all, pressurized air is just as good at driving a piston up or down—and potentially cheaper.

Such cars are not as fast as regular ones or anywhere near as powerful, but a tank of compressed air is enough to travel at least 60 miles, which is more than most Americans drive in a day. And as long as you don't need to go faster than 35 miles-per-hour, you won't need to burn any other fuel—meaning all that the only thing that comes out of the tailpipe is the same air that went into the engine.

Motor Development International (MDI) in Luxembourg has started working with Indian industrial conglomerate Tata to turn that company's forthcoming Nano car--the world's cheapest at roughly $2,000--into a compressed air vehicle. MDI has also paired with Zero Pollution Motors in New Paltz, N.Y., to make a similar vehicle available to U.S. consumers by 2010 , assuming all goes according to plan, at a price tag of around $18,000.

The buggies  may be cheap but pollution is another story. Setting aside other manufacturing issues, it takes electricity to compress the air. That electricity could well come from leveling a mountain in, say, West Virginia, to mine the coal needed (if produced by a coal-fired power plant), not to mention the carbon dioxide and other smog emitted while the coal is burned. But it still could be better than burning all that gasoline.

Credit: MDI