There are also various circuit and drift tournaments, pink-slip races where you put your car on the line (it's best to hold back on these until you know a track inside out) and drift obliterators in which you need to cross the finish line first, but also have to score a certain amount of drift points on each lap. Eliminator races see you spooking out opponents by driving up their arses until a panic meter peaks and they wipe out. As well as earning points towards unlocking the promotional event, some challenges reward you with bonus visual mods and bonus prototype mod packs to spend on extreme nitrous upgrades which you'll need installed to compete in any extreme nitrous challenge.
Customising your cars is one of the most satisfying parts of the game. Tuning packs for each league improve your motor's power, handling and weight, with the first of three packs for each area of the car already unlocked. The only way to unlock the next two pack levels is to complete one-off challenges such as finishing a lap in a set time without hitting any barriers, or beating a high-powered car in a one-lap race after being given a small headstart.