To change your car's appearance, go to the garage screen and select the Customize button at the bottom of the screen, or select the Workshop icon found on the race map screen.
Unable to change your car's color? Some of the cars in CSR 2 are limited in the colors available due to licensing issues.
You can also personalize your License Plates from the customization screen. Players you race in multiplayer will be able to see your custom License Plate.