As I was foraging for new engine news I came across this the other day and marked it for another look. Now that I've looked, I still have no idea how exactly this air car works. There is compressed air involved driving pistons, I think, and lots of talk on the site about energy recovery and whether the engines are adiabatic or isothermic, loads of jargon and slow loading graphs and pictures but I can't figure out what any of it adds up to. Actually, the key sentence in the whole site is: "For various reasons, one of which is industrial secrecy, we haven´t published all technical details on this site." Right. Translated: it doesn't really work like we say or at best, doesn't really accomplish anything. If you can't explain how it works in that many pages, chances are, there's nothing to explain.