Oh and in terms of solar cells on car bodywork that is not possible. Sunlight at peak is approximately 1kW per metre square. So assuming max surface area for car in plan view of 2 x 4 metres gives 8kW. But solar panels after lots of research still only 15 to 20%efficient. So we are down to roughly 1.5kW per car. Using Nissans figures for their Leaf car it needs 40kW/hr for 160miles. (Probably optimistic)
So one hour in the sun at midday in full sunlight will get us 6 miles down the road. This will decrease with time of day and weather and of course don’t park in a multi storey car park.