Ok now for the life of me I can not switch between the gat and the rocket's that I bought for my buggey's.In the setting's it is set to the mouse up or down wheel but it wont switch so I set it to the arrow up and down as the secondary option to switch the weapons and I still cant switch.Any one know how else to do this or is it some kind of bug.

scroll button

Im having the same problem. I cant switch from rockets to minigun no matter what keys i map next weapon or previous weapon. even the defaults dont work while in the buggy. HELLLP!!!!

Buggy does not HOLD both minigun and rockets. You need to get the next car, Cuprino, during the main story to use both weapons.

press R1 to switch but buggy cant hold 2 get the Cuprino

For the rat rod, go to the tune menu and switch guns under weapons