Ridge Racer 6 - Burningforce Highjack car

Dragonspirit Wild Gang car:
Complete race 16 to unlock the Dragonspirit Wild Gang car.

Gaplus EO car:
Complete races 16, 26, and 33 through 42 to unlock the Gaplus EO car.

Gaplus Fatalia car:
Complete races 3, 4, 5, 6, 8, 9, 10, and 11 to unlock the Gaplus Fatalia car.

Klik Starnose car:
Complete race 6 to unlock the Klik Starnose car.

Mappy Wild Gang car:
Complete races 7, 8, 9, 10, and 13 to unlock the Mappy Wild Gang car.

Mitsurugi Meltfire car:
Complete race 23 to unlock the Mitsurugi Meltfire car.

Pac-Man car:
Complete the Pac-Man Route 1 race/Duel.

Pac-Man mini-game:
Complete races 77, 102, 103, 104, 105, 106, 107, 108, 109, 110, and 111 to unlock the Pac-Man mini-game at the options screen.

Pac-Man Route 1 race/Duel:
Score over 15,000 points in the Pac-Man mini-game to unlock the Pac-Man Route 1 race/Duel.

Phelios Fatalia car:
Complete races 6, 10, 11, 12, 16, 24, 25, 26, 33, and 34 to unlock the Phelios Fatalia car.

Phozon Fiera car:
Complete races 1, 2, 3, 7, and 8 to unlock the Phozon Fiera car.

Shootaway Fatalia car:
Complete races 10, 12, 13, 14, and 15 to unlock the Shootaway Fatalia car.