Bonus Car
To get the Boss Car, press L + R + Up at the title screen. If
you did the trick correctly, you'll hear a
rumbling sound. Begin a normal game. When you reach the boss,
you'll be driving his car.
Overhead Camera
At the title screen, press Up, Down, L, R, Select. If you've done
the trick correctly, you'll hear an
explosion in the background. Now go to the Options menu and choose
Mystery Mode. You'll be able to play the whole game from an overhead
view.