All Cars, All Trophies:

At the Game Progress screen, press L1, R1, Left, Right, Left, Right, Up, Down, Up, Down, X, X + Select. You will hear a sound to confirm. Now press X on any car or trophy to unlock it.

Better Acceleration:

Type LDN as a driver name.

Look! Up in the Sky!:

Type _FLY_ as the driver name and you’ll fly... This can be used for big jumps. Do not forget the empty spaces before and after the word FLY!

Bonus Tracks:

Enter one off the following driver names, begin a race, and then quit. Start a new race, select a car, choose time trail mode, select "Corsica" and select any track to get to the following bonus location.
CBLC
CBLCA
CBLCB
CBLCC
CBLCD