If you want to skip the grind or just cause chaos, you can enter these in the menu (note: they are case-sensitive):

: Unlocks all cars and cities specifically for Arcade mode. System Requirements (PC)

: Unlike traditional track-based racers, you can drive anywhere in the city and find your own shortcuts to reach checkpoints first.

: Features include a white-knuckle career mode, arcade races, and a Capture the Flag multiplayer mode. Availability & Pricing

: In addition to performance-enhanced cars, this was the first entry to introduce motorbikes to the series.