Get Monster Truck
Go to dinosaur level and drive back wards for a long time.
Get Monster van
Go to swamp level and on the keyboard hit up and left or right keys.
Get Green Van
You'll need a joystick to do this. Go to the Garden level and on the joystick go side ways hitting the 3 and 4 buttons.
Get Tydied Van
Do the same thing that you did to get Green Van except you go to the beach level.
All Cars
Search the file named "carwheel" in 'stunt track driver 2/data/game' and change every 1 to a 0
All Tracks
Search the file named "track" in 'stunt track driver 2/data/game' and change every 1 to a 0.