Drive as a Tow Truck:
Go to race setup and choose car select. Select Bobby Labonte or Kenny Walace then hold C and press UP, DOWN . This doesn't work in 2 player mode.
Fast Car Mode:
Go to game options screen and highlight stereo. hold Z and press B then X then Y and simultaneously press A and B. You should hear "GO BUDDY GO GO" now start the race and press START + A + B + C. when the game reloads your car will be twice as big.