I'm not sure if this has ever been considered before, but I ran across some info about cavitating heaters aka "Water Hammers" a few days ago. From what I could gather, they create bubbles in a liquid by spinning a special rotor inside of a cylinder at about 3000 rpm using an electric motor. The forces inside the cylinder cause the bubbles to heat up very quickly. One of these devices is claimed to create steam within a matter of seconds.
Now suppose you scaled down one of these heaters for use in an electric car. The drive motor would be run by normal batteries, but the batteries would be recharged by a stirling engine powered generator. The stirling would in turn be run by the heat output of a cavitating heater. The heater could be on a seperate battery which could be charged periodically either by a roof mounted solar panel or a mains connection. From what I hear about these heaters, their suppose to be very efficent and I would assume that you could get pretty good mileage from a car. All the better if it were efficent enough to where only the heaters power source would ever need charging and not the cars main bank of batteries.
Just a thought!
RMG
http://www.overunity.com/index.php/topic,356.0.html
Thanks for the link, although I didn't find anything in it to suggest that someone had tryed coupling the heater with a stirling engine. Maybe I'll post under that link.
Thanks!