I'm already accounting for all that. Footprint of a car is close to 8-10m^2, that area of 20% cells with a 10-15% capacity factor (covering night and clouds) is 160-300 watts.

http://www.wolframalpha.com/input/?i=1kW%2Fm%5E2%2A8m%5E2%2A...

http://www.wolframalpha.com/input/?i=1kW%2Fm%5E2%2A10m%5E2%2...