One Stop Shop Marker:
Press Up, Up, Down, Down, Left, Right, Up, Down at the title screen. A special marker in the back room of the One Stop Shop will appear for the Junkman Engine.
Burger King challenge:
Press Up, Down, Up, Down, Left, Right, Left, Right at the title screen.
Porsche Cayman:
Press L1, R1, R1, R1, Right, Left, Right, Down at the title screen.
Castrol Ford GT:
Press Up, Down, Up, Down, Left, Right, Left, Right at the title screen.