The Dirt Runner is an unarmored and unarmed motorcycle that uses speed and agility to scout out areas, ride off-road and patrol AN areas. It has fairly good speed and allows the rider to get to places very quickly, and is also a good choice for cruising around the lake.
It has a good solid build unlike the civilian bike which practically falls apart the second a bullet hits it. It also has room on the back for an ally. However, it lacks the speed of other bikes and has deadly consequences for NPCs on the back if you crash, where other bikes tend to have a smaller fatality rate.
The easiest place to find one driving around is Caracas and any AN outposts the mercenary has taken over as part of outpost contracts for the Allies.
As the Dirt Runner is unarmored and unarmed, it is near useless in combat situations, aside from scouting out enemy outposts, and escaping and out maneuvering enemy fire.
It is best to use the Dirt Runner as a means of quick and cheap ground transportation.