Win the indicated Stock Car race near the airstrip in Grand Senora Desert to unlock the corresponding vehicle in your garage. Note: The Cheval Marshall Monster Truck will appear at Trevor's airstrip at Grand Senora Desert. These vehicles are exclusive to the PC, PS4, and Xbox One versions of GTA 5.

Race 1: Burger Shot Stallion.
Race 2: Redwood Gauntlet.
Race 3: Pibwasser Dominator.
Race 4: Sprunk Buffalo.
Race 5: Cheval Marshall Monster Truck.