Black helps to radiate heat more efficiently just the same way it helps to absorb heat better.
However in a car "radiator" or intercooler where the radiation aspect accounts for only about 3% of the heat transfer, it doesn't really matter whatever you do with the color.
Convection (from metal to air) is the main heat transfer method when air is flowing over parts to be cooled. With no forced convection (airflow from car movement or fan) the radiation aspect of heat transfer would be larger but still minuscule in comparison to other factors.
Edit:
socc924 said:
..Ive heard people saying that black will cool better then light colors, but im almost positive it would only have an effect when light rays are concerned. Im gonna research because i just dont buy it.
Radiation transfer works in the visible and non visible light spectrum. Just because humans can't see it, doesn't mean it's not there.