These codes allow you to play with any player including Olaf the Last Viking (hidden character) with a fully powered up car.
To drive anywhere on the track, go to Set Options, then press Down, Left, Up, Right, Down, Right, Up, Left, Right, Left.
At the main screen showing your racing stats, driver, money etc. Press Up, Right, Down, Left, Up, Left, Down, Right, Up. $250,000 will be added to your cash. You can do this as many times as you want.
These codes allow you to play as Snake with loads of money and a fully powered up car.