Do the amount of races required (DO NOT NEED TO WIN) for EACH of the vehicle class types to unlock their particalar customization upgrades. Tuners, Muscles, Luxury, Exotics, and Superbikes are the vehicle class types.

Unlockable	How to Unlock
Blowers	Do 45 races with a specific vehicle class.
Car Headlights or Motorcycle Bowls	Do 36 races with a specific vehicle class.
Car Spoilers or Motorcycle Tails	Do 18 races with a specific vehicle class.
Car Stereos or Motorcycle Tanks	Do 27 races with a specific vehicle class.
Exhausts	Do 45 races with a specific vehicle class.
Front Bumpers	Do 9 races with a specific vehicle class.
Front Seats	Do 27 races with a specific vehicle class.
Hoods	Do 36 races with a specific vehicle class.
Intercoolers	Do 45 races with a specific vehicle class.
Post Gauges	Do 27 races with a specific vehicle class.
Rear Bumpers	Do 18 races with a specific vehicle class.
Skirts	Do 9 races with a specific vehicle class.
Steering Wheels	Do 27 races with a specific vehicle class.
Taillights	Do 36 races with a specific vehicle class.
Widebody Kits	Do 45 races with a specific vehicle class.