The Mutant Bash Weapon is a Vehicle quick-use item featured in RAGE. It can only be used during the quest "Win the Dusty 8" when participating in the Dusty 8 Sponsored Event. It is a massive, blue, track wiping weapon featuring the face of J.K. Stiles and the letters "M" and "B". When used, it destroys any vehicles directly in front of the player's Buggy. It is accompanied by J.K.'s voice.
When using this vehicle quick-use item, it is best to use at bottlenecks when multiple Buggies have the chance to pass you. It is also very helpful when only one enemy vehicle has a slight lead against you, as this will immediately destroy them. Also, in the very last lap, it is best to use up your last one, just in case anyone is close enough to take your victory.