I even figured out that I could put a small wind turbine on my house that would charge a bank of batteries over 2-3 weeks so that I would have enough juice to run the compressor to refill the car. An entirely air powered automobile! It would work so great for me too - work is only 4 miles round trip so I should be able to go several weeks between fills no sweat!
And how's this for a bonus?
If I remember right, the cylinders are more or less 4500 psi cascade bottles. Now let's say a diver buys one... if it has a compressor capable of filling 4500psi bottles, it sure as heck can fill a scuba tank!
"Yeah, I added a hyperfilter to my Aircar, gets 120+ equiv-mpg and I can CB nitrox from the trunk."
Edit: just checked the stats, it packs 3200cf of air storage at 4500 PSI, with a 13.5cfm compressor, and has carbon filtration already on it from the factory. I have a sneaking suspicion they just took a scuba/scba compressor + cascade bottles and built their system around it, would make sense... its all readily available.
Price is $15-20k and they make a pickup truck version. I just put my name on their mailing list for announcements - I'm ordering one when they're available, heheh.
-B