There was a documentary about the Queens Univerisity Solar Team made some time last year about a solar car race.

Here is their web page:

http://solarcar.queensu.ca/mn_current_car.htm

Solar power is not yet strong enough to fully power a full sized car. The car is so skinny that the driver has to lie down do drive. There is only place for one passenger.

One of the biggest hitches...the sun's rays may be free but harnessing them is quite expensive. I can't remember the exact figure (Bean, help if you saw the documentary...it was Canadian so I'm sure our U.S. pals won't have seen it) but I seem to recall it was somewhere in the quarter-million-dollar range. No chump change let me tell you.