Steve is right, the reason fog lights have traditionally been yellow is that yellow light has a longer wavelength and thus, in theory at least, weaves through fog better (red lights would be even better because of red's even longer wavelength, but would obviously cause problems as front lights). Really, I think this is an area where theory is nice, but the practical gains are minimal. So get whatever color you want. But, being an old person who once had yellow Hellas on my '77 BMW, I take offense at the WalMart reference. I got mine from a high-end foreign car parts store some distance from my trailer park.


2000 Contour SE Sport T-Red MTX, Mystique rear dome light, Blau Florida cd.