With all the vehicles on the road this day and age. Why not have a 3 foot x 3 foot solar panel located on top of the roof somewhere? Cars could be larger than a pickup's. Even the top of semis and trailers could use this. Now this of course can't keep up with the alternator to charge your battery, but it would provide a slow trickle charge to your battery. In cold places this would do wonders. Picture in your head all those parking lot full of cars each day. Miles of vehicles driving in traffic down in California. We potentially waste so many opportunities to use solar panels.