The gameplay on the Sony PSP versions is similar to the console versions in that the player has to win various solo and team championships to unlock new tracks, new vehicles and unlock new tournaments to earn cash to purchase those newly unlocked vehicles and/or repair the ones they currently own.
The gameplay on the Sony PSP version mirrors the console version's mechanics: winning races unlocks new content (tracks, vehicles, tournaments) which players can then use to earn more cash for upgrades and repairs.