Its bad luck to have a green race car, or a number on a race car that can be read upside down (11, 88, 69, etc) or to have peanuts anywhere near a circle track.

A good friend of mine was building go-kart motors for a kid and somebody brought peanuts into the track. They dropped a couple of shells into the seat. That same night the kid wrecked and broke his leg. It goes back many years, but its definitely a no-no to have peanuts at the race track.