A rumble seat for increasing passenger capacity of a motor vehicle by at least one occupant includes a combination seat back frame and roll bar moveable between a retracted position and an extended position. The combination seat back frame and roll bar can be selectively operated for carrying at least one additional passenger when in the extended position, while providing a substantially uninterrupted exterior motor vehicle contour when in the retracted position. A track mechanism and a plurality of rotatable elongate linkages can be provided for guiding movement of the combination seat back frame and roll bar between the retracted and extended positions. The track mechanism can include a guide track having an L-shaped configuration with an upper horizontally extending segment and a lower vertically extending segment.