Secret Option Menu:
At the pause menu, highlight " race statistics", hold O and press X.

Colored Cars:
Start a new race and then select the 'begin career' option. Then enter the following codes on the 'Register' screen:

Go Bears!  = Stock Cars

Go Bruins! = Formula One cars
On the car selection screen, the cars will have different logo's and different colors.

Edit Cars:
During a race, press 'start' to pause the game. Then position the cursor over ' Race Statistics'. Then hold L1, L2, R1, R2, X, O, Select. A new 'Secret Car' menu will appear. This menu will allow you to change some features of the car setup.