Smashing !
Whenever playing in a race (I prefer the Slag Brothers) try bumping nearby racers. Don't slam from behind, instead, be pararrel with the racer and take a turn into the racer. Sometimes you may jump in the air and lose speed.

Unlock All Tracks And Characters
Curses! Foiled again!
Don't give up! Cheat! Try this code on for size. From the Main Menu enter the Options Menu. From here select Password and enter:
MUTTLEY
This will unlock all of the Wacky characters and Tracks