Fat Car Mode
Go to the game options screen and highlight stereo. Hold Z and press B
then X then Y and then simultaneously press A and B. You should hear
"Go Buddy Go Go". Now start the race and press START+A+B+C.
When the game reloads your cars will be twice as wide.
While practicing, qualifying or racing, pause the game and go down to
Race Stats. While it's highlighted, hold L-shift + R-shift + Y and
press A or C. This will let you control more aspects of your vehicle.
To reset the game, hold A+B+C and press START.
Enter the the wireframe track code and start the race, then press
START + A + B + C to restart the game. Now cars are wireframe too.
Go to the game options menu and highlight control setup. Hold Z and
press A then B then X and then simultaneously press A and Y.
You should hear "Go buddy go go". Start a race and it will be a clear track.