All cars:

Enter GANGS_UNLOCKED as a password for all cars. Note: This does not 
unlock the UFO. 

Y The Alien:

Enter GIMME_DA_ALIEN as a password. This character is normally 
unlocked after completing quest mode using all other characters. 

All characters and levels:

Enter JTBT7CFD1LRMGW as a password. 

Same vehicle in multi-player mode: 

Enter MIX_MATCH_CARS as a password. 

Ultra-high resolution mode:

Enter MAX_RESOLUTION as a password. Note: This code requires the 
memory expansion pak. 

Interceptor Missile power-up:

Enter MISSILE_ATTACK as a password. 

Invincibility:

Enter LIVING_FOREVER as a password. 

Big wheels:

Enter MONSTER_WHEELS as a password.

Quick firing weapons:

Enter FIRE_NO_LIMITS as a password. Note: This does not effect the 
machine gun. 

Low gravity:

Enter A_MOON_GETAWAY as a password. 

No enemies:

Enter POPULATION_OUT as a password. 

Slow motion mode:

Enter GO_REALLY_SLOW as a password. 

Expert mode:

Enter I_AM_TOUGH_GUY as a password. 

Level select:

Enter LEVEL_SHORTCUT as a password. 

View ending sequences:

Enter LONG_SLIDESHOW as a password. View any character's ending to 
see all the game's endings in sequence. 

Super Dreamland 64 level:

Enter DDDDDDDDDDDDDD as a password. 

Special weapons:

Enter the following actions during game play to active the special 
attack of the indicated weapon. Note: The required weapon must be in 
the inventory, but does not need to be currently active. 

Interceptor Missiles (Halo Decoy), uses 2 missiles
Press Up(2), Down then shoot the machine gun to cause your opponent's 
homing missiles or special attacks to follow your missiles instead of 
your vehicle. 

Interceptor Missiles (Turbo), uses 2 missiles
Press Up(3) then shoot the machine gun to speed up for a few seconds. 

Bull's Eye Rockets (Stampede), uses 1-5 rockets
Press Up, Down, Up then shoot the machine gun to rapidly fire 
multiple non-homing rockets. 

Bull's Eye Rockets (Boost Rocket), uses 2 rockets
Press Up, Down, Down, then shoot the machine gun. If an opponent is 
hit, he or she is taken for a sky ride. 

Sky Hammer Mortar (Turtle Turnover), uses 2 shells
Press Down(3) then shoot the machine gun to flip your opponents' 
vehicles. 

Sky Hammer Mortar (Crater Maker), uses 5 shells
Press Down(2), Up, then shoot the machine gun to drop a mega bomb 
that will leave a crater. 

Bruiser Cannon (Cow Puncher), uses 2 shells
Press Down, Up, Down then shoot the machine gun to punch opponent 
vehicles back. 

Bruiser Cannon (Scatter Blast), uses six shells
Press Down, Up(2), then shoot the machine gun to shoot six cannon 
shells simultaneously. 

Roadkill Mines (Cactus Patch), uses 1-6 mines
Press Left, Right, Up then shoot the machine gun to rapidly deploy 
a group of mines. 

Roadkill Mines (Magnetic Mine), uses two mines
Press Left, Right, Down, then shoot the machine gun to drop a mine 
that will attract nearby cars. 

Hint: Control the blimp:

Drive around the blimp in Casino City. Drive inside when the back 
door opens to steer the blimp around the level.