Through out the game,Shadow the Hedgehog,it appears that during stages GUN has left(or lost) their vehicles,appearently allowing the player to take control of them.You can accelerate them by holding on to the X button(PS2)and the A button(Gamecube and Xbox)(or some with the analog).
GUN Bike:It is a average speed bike(therefore,difficult to handle)found in various stages.
It is a slow,Heavy and strong automobile found in various stages.Thus,it is the first vehicle found in the game.
GUN Heavy Car:
This basically is a type of cameo and not particulary even to the GUN vehicles but then it is still found in the levels.It is very fast and bouncy in the game.
GUN Truck: It is a very strong and useful truck that has the ability to crush most of the enemies in the way.It is only found in the level GUN fortress.
GUN shooting vehicle: It is a type of robot that is fully armored and slow.It isn't really found in gameplay(maybe 1 level)but in multiplayer mode.It can also shoot bullets.
GUN high jumping machine: Again,it is a type of robot that has the ability to jump very high,it is also very good for short cuts.