Key points of GTA V Map - Tuning
In GTA V you find a lot of races, especially the street ones. So you'll need a quick car, won't you? To get one, find any car and head for one of Tuning Parlors - Los Santos Customs.
A little twisted, but it'll work.
The most tuning options is available for sports car: you can change bumpers, add spoilers and many, many other.
Such parlors can also save you during your escape from police. Just ride into one of them (make sure that there is no police car next to you) and change your car color. Stars should disappear and you can freely ride out.