To unlock these vehicles, play Arcade, Time Trial, and Championship modes.

Vehicle	How to unlock
Flying Mantis	Complete Twinloop Circuit in Arcade mode.
Forkster	Complete the Championship, then finish second on Freefall Freeway.
Formula 17	Beat the target lap on any track in Time Trial mode.
Inferno	Complete Waterfront Dash in Arcade mode.
Road Hog	Complete Flying Finish in Arcade mode.
Team Machine	Beat the target lap on every track in Time Trial mode.
The Hustler	Complete Roughdust Flats in Arcade mode.
The Phantom	Complete Intersector in Arcade mode.
Twin Eagle	Complete Highfly Clearway in Arcade mode.
Wild Dart	Complete every track in Arcade mode.
Worms Mobile	Complete the Championship, then finish first on Freefall Freeway.