That is the reason you don't see to many black airplanes. Besides making the interior very fecking hot, it is very heavy paint and costs in fuel burn.
I can't remember the number, but American actually has a stat on how much money they save with polished vs painted planes.
Here is one to think about...... The avg plane has around 200-300 pounds of dirt and grime clinging to the surface of the entire airplane right before washing. Think about how much that costs to fly around.