Instructions
Finish the game's Adventure mode and collect all platinum relics. In the Adventure mode, players must complete a series of races before finally racing against Nitrous Oxide. At the end of each level, players compete in a relic race which allows them to collect relics by breaking certain records. Platinum relics are the most difficult to obtain. Collect all of them and defeat Nitrous Oxide, the final boss, to finish the game.
Beat all of N Trophy's ghost cars in Time Trial mode. N Trophy is another CTR villain, and you can race against a ghost version of his car in Time Trial mode. You must perform this step in order, starting with track number 1, Crash Cove.
Beat all of Nitrous Oxide's ghost cars in Time Trial mode. You must again perform this step in order, starting with track number 1, Crash Cove.
Hold the L1 + R1 trigger buttons and press the Right, Circle, Triangle, Left, Down, Circle, Triangle, and Left buttons at the title screen of the game to finally unlock Nitrous Oxide as a playable character.