I remember working on solar powered cars back in college.
basically, they were 4 wheeled bicycles that couldn't really get up to freeway speeds.

Currently, if i wanted to charge my car with solar panels, i would need about 6x the size of the car parking spot for normal daily driver usage numbers. Soooo, a really big carport, for one car to charge.

I haven't seen the solar panels get all that much higher in efficiency... but hey, if you live in Phoenix, AZ, and park outside, it could save half your charging bill. (your mileage may vary, not available in all states...)