Photos: MiniCat car runs on compressed air

Here's where you fill 'er up with compressed air. The air drives the pistons in the engine, and the engine returns the favor by recompressing air for later use. It could take four hours to refill the tanks via that method, but "the tanks can be refilled with high pressure in three minutes at an air station," the company says on its Web site.

The compressed air engine is supplemented by an electric motor, and the latest versions of the cars also include a fuel engine option, according to Reuters. The top speed of the cars, which top off at about 330 kilograms, is 150 kilometers per hour.