ATV (RF2)
The ATV is one of the various land vehicles in Red Faction II. it is purely an enemy vehicle and can never be entered, featuring dark tinted windows that show reflective surfaces. The ATV does have turrets on top of it, and sometimes attacks the player during Tank On The Town.
The ATV is also a feature of several missions "Bonus Objectives" in which killing them gets you a boost to your Heroics meter.
Outside of these instances they appear to be purely decorative for the games military environments.