Solar power is kinda hard to capture. Even if a car was solar powered, it wouldn't run very fast. I remember seeing a solar car in person when I was in 5th grade. It could barely go more than 30 mph. And even if you do store the power, it would run out in about half an hour. And AC, radio, heat, etc. would run down the battery quicker too...but eh. It could be a combination of all three, gas-electric-solar...that could be the ultimate and most convenient way to build a car's fuel source.