Complete all of the novice tracks to unlock 3 new cars.
In addition to the three Beetle Battle arenas you begin with, you can unlock 6 more. To do so, go to Championchip mode and collect all 100 points worth of boxes on a course in one race.
Beat Expert Championship to unlock the ''Alien Beetle''
Race on the Coventry Cove course in Championship mode until you see a barn on the right side of the road with two haystacks in front of it. Drive through the hatstack on the left and you will smash a hidden crate with a picture of a flower on it; you'll also hear a voice say, ''Groovy!''. Note that the crate will not be there unless you are playing in Championship mode. Once you've smashed the crate, finish the race; the words ''Cheat Menu Activated'' will appear at the Player Results screen. Now return to the main menu and access the Options screen; you'll find a new option called ''Cheats'' at the bottom. Each item on the cheat menu must be ''unlocked'' before you can used it; you will unlock a new cheat each time you smash a flower crate in Championship mode. Some of the crates are very well hidden, so you're going to have to do a lot of searching to find them.
Expert Diffculty Is Hidden, Unlocked By Winning Professional Circult In Championship, Expert Diffculty Will Become Revealed