When driving at night, what colors on cars are easier to see and what colors are harder to see?
At night, your rod system often becomes more important than your cone system for seeing objects. The rods are sensitive to shorter wavelengths than the cones. (This is why red objects tend to look black at night, the rods simply don’t respond to red light.) The easiest things to see are those that contrast most with the background. Assuming the background is dark, you want cars that would appear light. White will always be a good choice for this since it is lighter than the background for both rods (when no extra light is on the car) and cones (when headlights are shining on it). As far as chromatic colors, a light blue would probably be then next best choice. As I mentioned above, red would not be good since it would look black to the rod system. A yellow color would probably end up somewhere in between; nice and bright for the cones, but a bit darker for the rods.
