Compressed air is a pretty amazing way to do alot of things. You can use pneumatics to power just about anything if you have enough pressure.
I wish I could find the link to the older "Air Car" design that was 100% pneumatic. I think I ran across it on wiki... I know they have a thing on there about the nitrogen powered car. That was pretty cool too.
I think this is great too; I'm a big fan of alternatives to fossil fuels. Please note, though, that this does not run purely on air. To achieve speeds above 35 miles per hour, a fuel source is needed to heat the air. Still, it's likely to make an impact.