The Posterior of Randal Schwartz

Compressed air is certainly not free, it takes electricity, from coal fired powerplants, for example. This is, of course, not perpetual motion in any sense. I'd have to see the energy cycle of the whole system before I'd believe it's a lot more environmentally friendly than the most efficient gasoline powered cars.

Anyway, it's a cool concept. I think Tata is attempting to produce an air car for India.