Original URL: http://www.psxextreme.com/psp-cheat-print/106.html
Cars
New Paint Jobs

Each car has a total of 3 alternate paint jobs. Go into time trial mode and finish within the appropriate time limit to unlock a new paint job. Finishing 3rd will unlock one, 2nd will unlock two, and 1st will unlock all 3. Below is the required track for each car.

Lightning McQueen - Figure 8 Track
Mater - Desert Canyon Dash Track
Sally Carrera - Radiator Springs Track
Wingo - Interstate Track

Unlock Boss Cars

Simply beat each car in story mode (DJ, Snot Rod, Wingo, Boost and Chick ) to unlock them.

Other Unlockable Cars

Doc Hudson - Finish the first Gran Prix Cup
Sheriff - Finish the second Gran Prix Cup