300 mph car
At the car selection screen, quickly press Circle, Square, L1, R2, Right, Left, Up.
At the car selection screen, quickly press Up(2), Down(2), Left, Right, Left, Right, Square, X.
Finish all classes in all championship categories. Then, make a car and enter "Fusshusama" as a name. Enter "Bye Seya" as a team name.