California Speed
Move The Screen
Hold L, R, and Start at the same time during a single player race on controller #2. Then just move the analog stick!
Credit Goes To: kenny7742 via N64cc
 Move The Screen
 Secret Tracks
 Mirror Series
 Shortcut in Mt.Shasta
 Secret Cars
Secret Tracks
After you get to the third week of any of the series car classes you'll see a track with ? on it. get to that track and you'll unlock it! here is the tracks for the following series.
Oval - Complete Week 2 of the HeavySeries
Mt. Fugi - Complete Week 3 of the Sport Series
San Andrias Fault - Complete Week 3 of the Heavy Series
California - Complete Week 5 of the California Cup
Clover - Complete Week 2 of the Sport Series
Credit Goes To: bconn2@hotmail.com via N64cc

Mirror Series
Go into Practice. Before selecting a track make sure that you set it to "Mirror." Go into the Practice track; but you don't have to race the track. Simply exit and start a "Series" race. Now you can race the "Series" in Mirror Mode. Go back into Practice and switch "Mirror" off to switch "Mirror Mode" off.
Credit Goes To: Pokedweeb via IGN 64

Shortcut in Mt.Shasta
Right after the first turn there will be a break in the trees on the left go through there and it will cut some time off of the race and most likely you will pass up to about third place.
Credit Goes To: Hornetsrul@aol.com via IGN 64

Secret Cars
Five-Oh Car - Successfully complete the Sports Series.
Semi Truck - Successfully complete the California Cup.
Predator Car - Successfully complete the Sports Series with the Five-Oh Car.
Mountain Dew Pick-Up - Successfully complete the Heavy Series.
Squirrel Car - Successfully complete the light Series.
Mano Car - Successfully complete the Sport Series with the Predator car.
Insect Car - Successfully complete the Light Series with the Squirrel car.
Forklift Car - Successfully complete the Light Series with the Insect car.
OL' Truck - Successfully complete the Heavy Series with the Mountain Dew truck.
Camper truck - Successfully complete the Heavy Series with the OL' truck.
Dozer Truck - Successfully complete Do The State with the Semi truck.
Credit Goes To: Brandon F.(Beater2_9@yahoo.com) via N64cc