When I was growing up, back in the Paleozoic era, I’m pretty sure it was illegal to have a red light on the front, white light on the back(except for backup lights), and blue or green were illegal anywhere on a vehicle. But all that seems to have gone out the window since then.
Of course any vehicle that’s been modified to produce excess smoke violates federal (EPA) and possibly local law, but we see how well that’s enforced.