Select single race mode, then press L1 + R1 at the difficulty selection screen to display the "Ace level" option.

Instead of allowing the game to idle until demo mode begins, press Triangle at the main menu. Each demo will play in sequence.

Complete 75% of the races to unlock the ending FMV sequence at the game status screen.

Win all races in single race mode under the normal difficulty setting to unlock an option at the game status menu to give 10,000,000 credits and a Bronze trophy for all licenses not already unlocked to a save file for Gran Turismo 3 A-spec.

Alternately, successfully complete 50% of the game. If you have a Gran Turismo 3 A-spec game saved on your memory card, you will get 10,000,000 credits and new licenses for that game.

Getting silver or gold on all course licenses

Choose "Yes" prompted to use the pace car just before you start your course license test. It helps you get at least a silver trophy, or even gold trophy on the particular test / tracks you are doing (for example, Tokyo R246). Take over the pace car and try to cross the finish/start line before the pace car does. However, on the rally course license tests/tracks, you may not be able to see where you are going due to the dust given out by the pace car. But, it still helps you to get at least a silver trophy.

Complete 50% of the races to unlock the Gran Turismo Concept 2001: Tokyo FMV sequence at the game status screen.

Get Golds on all the tracks in intermediate mode in single race mode.

Successfully complete course license mode with a bronze or higher rank to unlock the "Pod Race" option at the game status menu.