Tom Chick wrote:

It's a huge help that the experience point system has personality. There are two separate categories of experience: one for driving clean, and one for driving dirty. They're called precision and aggression, respectively, but we know what they mean. Each category has a set of actions that award experience points. During a race, if you push precision or aggression high enough, you'll earn double points. At the end of the race, you see exactly how many points you earned from exactly which actions. It's a clear-cut above-board system of actions and consequences.