Enter the following codes at the Campaign / Bonus Features / Credits menu:

Unlock Generation 1 Jazz Repaint - Left, Up, Down, Down, Left, Up, Right
Unlock Generation 1 Starscream Repaint - Right. Down, Left, Left, Down, Up, Up
Unlock Cybertron missions - Right, Up, Up, Down, Right, Left, Left
Unlock Robovision Optimus Prim - Down, Down, Up, Up, Right, Right, Right
Unlocks G1 Megatron - Down, Left, Left, Down, Right, Right, Up
Unlock All Mission - Down, Up, Left, Right, Right, Right, Up, Down
No vehicle's running on the street and no tank's/cop's attack - Right, Left, Right, Left, Right, Left, Right