Enter Bart, Bart, Lisa, Lisa, Marge, Marge, Barney, Barney as a password.
Burst of speed
When starting a roadrage at the last moment press A, you'll get a burst for one second or as soon as a passenger lands in the car press A. Note: its easier as soon as a passenger gets in.
Extra speed
Enter Maggie, Bart, Maggie, Willie, Mr.Burns, Bart, Marge, Barney as a password.
Finished Game
Enter Maggie, Willy, Bart, Chief Wiggum, Apu, Moe, Krusty, Barney at the password entry screen.