My father in law is a paint weirdo and gets free returned paint from Home Depot. He mixes his own colors from that supply source and so whatever colors he gets free are what he paints his house, just because he can. I wish I had that kinda free time to blow on painting something that doesn't need painting.......... Anyhow, point being is for some stupid reason he decided to use some royal (dark) blue in his garage and the atmosphere is depressing and obviously dark. So in addition to the floor being bright for reasons the other guys said, don't do walls (or ceiling- yes, FIL painted the ceiling blue too....) dark either!
Garages seem to be light-challenged, especially when they're an attached garage. So light colored walls and floor are helpful in brightening a typically dark place?