Performance Parts
Finding parts
Performance parts (intakes, turbos, exhausts, superchargers, clutches and more) turn up when you collect a finished work-bay job: about 1 in 16 for a five-minute job, up to 1 in 2 for a two-day one. Rarer parts turn up less often. You can hold up to 200.
Parts mystery boxes in the car shop's crate tab hold one part each, with a better chance of 4 and 5-star parts. Buy one, put it in your garage, then click it to open.
Fitting a part
Open Upgrades on the bottom bar, pick a part and choose Install, then the car. Each part says which cars it fits (a class, a make or a decade). One part fits on a car at a time and adds to its performance. Fitting costs coins (or blue points), more for faster cars; taking a part off costs 30% of that.
Tuning
Tune merges spare parts into one to raise its level: every level adds more performance. Rarer parts reach higher levels. Tune Juice is made only for tuning.
Selling
Spare parts sell for coins: Sell in the Upgrades list.