Years-old, off-the-shelf technology uses compressed air to drive old-fashioned car engine pistons instead of combusting gas or diesel fuel to create a burst of air to do the same thing. On highways, the CAV can cruise at interstate speeds for nearly 800 miles with a small motor that compresses outside air to keep the tank filled. The motor isn't finicky about fuel. It will burn gasoline or diesel as well as biodiesel, ethanol or vegetable oil. Even if it used only regular gasoline, the air car would average 106 mpg, more than double today's fuel sipping champ, the Toyota Prius. The air tank also can be refilled when it's not in use by being plugged into a wall socket and recharged with electricity as the motor compresses air. More info here.