So I was watching beyond tomorrow today, and they did a bit about a very cool little engine. It's a rotary engine that weighs just 12 lbs and runs off of compressed air... what's so cool about it is that it has enough power to pull 2 tons, and can go fast enough to take a car on the freeway. They did several demonstrations of it, and the inventor has already put it in several different types of vehicles to demonstrate it. The vehicle he put it in looked like a honda civic type vehicle (it was in Europe, so I'm not sure that's exactly the make/model, I didn't get a look at that), and with the air tanks he had in it, it took him 2 and a half minutes to fully charge the tanks, and it ran for about 100km off that. He also put it in a forklift and boat, and looked like it worked well in the forklift (not so much in the boat, but they may just not have opened up the throttle on it, they only showed it for about a second as they were pulling away from the dock). Another cool thing about it is that because there's almost 0 friction in the engine (most of the moving parts don't touch anything because they are cushioned by a thin layer of air is how they described it), it looks like it wouldn't wear out.
This thing looks like it could be the answer to high gas prices. Of course, I'd want to put in bigger air tanks, but that's easy enough that anyone could do it. Sure the electricity to run the compressor still costs money, but running a compressor all day is still cheaper (by far) than what I spend in gas for just an hour of driving.