I saw this idea for the zero emission air car and thought it sounded pretty cool except for the fact that it still requires energy to compress the air that push the pistons to provide drive. I was a little more skeptical when they start talking about how the engine that drives the car could also re-compress more air. My old college physics keep reminding that simply releasing the air will also release energy that can not simply be bottled again. Whenever someone talks about perpetual motion outside of perfect vacuums I get very weary.
Cool video none the less.