Use the following trick to get free parts without completing the game. Go to "Garage" and "Customize Your Car". Go to "Performance Parts" and press X to auto upgrade. This will check off all parts you can put on. Do not press A. After you press X, press Xbox 360 Logo (guide). Go to your friends list and join someone's session. Note: You can also join the recent players list for a better chance of someone playing online. When asked if you want to start a multi-player match, select "OK". When you get on the street, you will have the parts installed with no money deducted from your bank. This also works on any interior or exterior part, but the process is slightly longer to make the car you want. For example, highlight "Front bumper" then press X. Go to the bumper you want and press Xbox 360 Logo. Join someone's game, and when you roll out of the garage you will have that free bumper. Quit the multi-player game, return to the garage, and get any other part desired by doing the same thing.

Note: This trick only works on cars that can have sidepipes (muscle cars). Use the following procedure to get free side exhaust pipes. Enter the garage and select the muscle car of your choice; make sure it can have sidepipes. Go to "Customize Car". Go to "Side", and select "Side Exhaust". Highlight the exhaust of your choice and press B. Go back into "Side Exhaust". The pipes you want will now be $0.