To enter each code, go to the 'Bonus' section of the game's options and enter the code you are given into the 'Enter Bonus Code' section.
Complete the entry by selecting the return icon at the end of the list of letters. The codes are activated when a tick appears next to them in the 'Activate Bonus' section.
Enter DBXLMNAN to unlock all the cars and championships except the last 3 bonus Championships
Enter LLNWQCKO to unlock the 3 special bonus Championships and all the cars
Enter NYOOKJKW to double the available engine power for all cars, including the AI cars (XBOX) or to increase the overall speed of your car (PC)
Enter REGOCNYO to swap Frontwheel drive cars to rear wheel drive and vice versa
Enter URPPSHYI to make the cars undamagable
Enter PDICULGR to unlock all the cutscenes