Mounted weapons can only be purchased with RP at Weapon Caches.
You can only have one type of weapon installed at a time.
There are 2 types, the mounted machinegun and the rocket launcher.
Both weapons can cause care to blow up, althrough the mounted machinegun takes a few shots while the rocket launcher only requires 1 direct hit.
Rockets explosions have a large area of damage that can also cause chain reaction explosions. Rockets can also easily blast through other obstacles such as barricades, trees and very large vehicles.
Ammunition for these mounted weapons cannot be replenished and therefore need to be repurchasede when they run out of ammo.