Get Cheat Mode Option:
After unlocking any cheat you will get the Cheat Mode option on the options screen.
Get 2 Player Pursuit Mode:
Beat Pursuit #3
Get Driver's Ed Car:
Finish driving 101 and get all gold medals
Invincibility Cheat:
Finish all the Grand Prix Championships with Gold medals to unlock the Invulnerability option in the cheat menu
Get Runaway Cheat:
Finish all the Crash Mode with Gold Medals to unlock the Runaway Option in the Cheat Menu. This option is like Crash mode with no brakes or goals. R1 will give you a boost if pressed at the start
Face off mode:
Finish all races in championship mode with gold medals
hints for offensive driving 101:
In the test in Offensive Driving 101 where you must get air over jumps, At the beginning of the level, turn around until you hit the red barrier, then go the right direction and get as much speed as you can over them.
Speed boost at start:
At the start of the race just after it shows 3-2-1. on the 1 do the tyre burn (press square then x)and you will get a huge speed boost at the start of the race.