OK let me git this straight:
White is derived by combining all the colors in the spectrum and black is derived by the abscense of any color. The speed of light is directly proportional to wave length of the color. For example blue is 5.5 microns and red is somewhat longer in the neighborhood of 7 microns I think, therefore I would conclude blue would be a tad faster than red).
Now considering:
The weight of the paint and the inclusion or exclusion of stripes has some bearing on speed as well. For example more colors must be mixed to obtain silver, grey etc. would add to the weight and the inclusion of stripes add to wind resistance and weight.
Therefore:
I would have to conclude that the closer you are to white in the color spectrum the slower. (eg yellow is very near white)
This means black with no stripes or roof (extra weight) is by far the fastest given equal driving ability of course.
and as far as sex appeal black wins hands down.