There has been some work done, looking at car, color, and interior color, and it’s effect on how hot the car is and then how much energy it takes to run the air conditioning to cool the car. Also, a cooler car can have a smaller air conditioning unit. Course with the windows open it makes less of a difference, because the windows being open creates Drag. I think it’s pretty clear a darker colored car is hotter than a white car. But it never made enough of a difference for the auto manufacturers to touted as a benefit, or for the regulators to insist on technology.