Access All Cars:
At the car select screen, press and hold in order R1 + R2 + L1 + L2 + Select + Down + Triangle.
Race only During the Day:
At the track selection screen, hold L1 + L2 and press X.
Race only in the Evening:
At the track selection screen, hold L1 + L2 + R1 + R2 and press X.
Race Only at Night:
At the track selection screen, hold R1 + R2 and press X.
Time Trial Mode:
On the track selection screen, hold Select.
Overhead Replay View:
During the replay, press Circle + Triangle + Square + X.
Finish in first place on all three tracks with the settings on normal enemy level and orthodox race style. Four additional cars (two different cards with automatic and manual transmission versions) will be available in the car selection screen: Red #1 (automatic), Blue #11 (manual), Yellow #2 (automatic), Green #12 (manual).
Racer X's Car:
Finish in first place on all three tracks with the settings on normal enemy level and endurance race style. Racer X's yellow #9 car will be available in the car selection screen. The light yellow car has an automatic transmission. The dark yellow car has a manual transmission.
Enable the "Extra cars" and "Racer X's car" codes. Finish the first trace in first place using Racer X's #9 car in Time trial mode. A red Demon car with a automatic transmission, and a black Demon car with a manual transmission will be available in the car selection screen. Note: These cars are called Ogre cars in the Japanese version of the game.
Race on the medium or hard track and go through the tunnel. Look on the left for a small passage with a wall. To break through the wall, go over 190 mph, bump the statues on the left out of the way, then use the saws to crash through the wall. Drive straight ahead to find the white GSX car. It has A++ ratings for auto and manual.
Two extra views:
During a race pause the game and press right five times then left five times. Unpause the game and use the zoom button to get different views.
Extra Vehicles 800a2220000c Low Time 800a06d80000 800ec64c0000 Place 1st 8010180c0001
Thanks to Revolution readers smurphs, Jack Posobiec, Rajat Bajaj and AnarkyToad!