red means go

So in  the 40k universe, Orks are amazing creatures. If they think something, it becomes true. If they think a gun will work, it does. One of their abilities is that if they have or get a vehicle, and it is Red, It suddenly goes much faster than it should, just cause they think Red things go faster. Kinda like the joke about ricer cars with custom paint jobs with racing stripes or decals. Orks are the guys in fast and the furious, cept for them Red means go!