In reply to:
Now, all this said, someone pointed me at a new idea which looks interesting.
http://www.theaircar.com
Yeah I saw a presentation on that about 18 months ago now.
Very nice idea.
The other point is that the cars themselves are all solid-colour plastic panels, so if you scrape the car, the colour stays the same. And if the panel is too badly scratched or otherwise damaged you just replace it and recyle the old one - and being plastic it never rusts - just gets brittle and fades due to increased UV from the ozone hole :-(.
Only thing I noticed about it is that the engine note sounds funny, kind of like a sick 2-stroke lawnmower. The only emissions though are air from the exhaust pipe.
According to the info I saw the "energy density" [Watts per kg] of compressed air is pretty high, coming close to that of carbon fuels.
I like the idea too that you recharge it by either filling up with compressed air at a service station [like with natural gas or petrol] or by plugging it into the mains and run the things "in reverse" while parked to compress air back into compressed air "fuel".
Of course it had better be quiet doing that [recharging from the mains] or no-one will plug their car in at home or work due to the noise if makes.
Of course, its not like fossil fuels were you get energy/something "for nothing".
You have to make the energy to run the compressor or make the compressed air some other way.
Which it seems they have thought about - turning motion directly back into compressed air removes wastage involved in making electricty then running a compressor to make the compressed air.
And of course, if the car crashes, the compressed air won't catch fire or explode like other compressed fuesl can do.
I'm sure if the cylinder ruptured the nett effect would be like a small bomb, but thats a danger with any compressed fuel being stored at high pressure.
I'd buy one tomorrow if they were available down here.