Unlock all tracks and arenas in Champoiship mode. Then, get first place in all arenas in Destruction Derby mode to unlock Rough Justice and bonus cars 1, 2, and 3.
Unlock all tracks and arenas in Champoiship mode. Then, get first place on all tracks in Wrecking Race mode to unlock The Dam and bonus cars 4 and 5.
Win all Races and Destruction Bowls in Single Races to gain access to a bonus bowl and a bonus track.
On the Refinery stage, once you beat Brennan he will become a playable character in the game.