We have motorcycles, but not quad ATV's? I personally have always liked quads more than dirt bikes, and I think they'd be as fun as hell to ride around on BL. A Couple different types would be nice to have:
Light: They'd accelerate quickly, be slightly maneuverable in the air, and it's max speed would be close to the jeeps max speed, higher or lower, I don't really care
Heavy: Wouldn't accelerate as fast as the light quad, but it's max speed would be higher, it wouldn't be as maneuverable in the air and it would weigh more, but it could scale steeper walls and stick to the ground better, and hold 2 people maybe
Light
Heavy