Ace mode:
Highlight the "Hard" selection on the difficulty selection screen.
Hold L1 + R1 until it changes to "Ace".
Alternately, complete 100% of the races.
All licenses:
Successfully complete the Toyota Pod Event.
Extra credits for Gran Turismo 3 A-spec:
Complete 50% of the races to unlock a saved game file
with 1,000,000,000 credits for Gran Turismo 3 A-spec.
Bonus FMV sequences:
Complete 100% of the races to unlock two FMV sequences.
Sites: