here's a link to flywheel recovery page 98
Popular Mechanics - Google Books
But as far as compressed air goes I think one of the best design is Di Pietro rotary air engine.-
info Also EPIndustries has a unique design of a motor/pump that seems to have a pretty good output-
CEM Co. Carbon fiber can be built to be extremely tough. I remember seeing a video on youtube of a carbon tank filled with hydrogen being shot at with 50cal guns. I would think that an air powered vehicle would be about as good of a choice as electric plus you would have a quicker refill.