The rear unit comprises first and second doors for a motor vehicle. The first and second doors respectively comprise first and second tailgates, the second door carrying the first tailgate. The first rear door has hinge means for hinging the first tailgate relative to the body of the motor vehicle, which means are fastened to the first tailgate. The first tailgate is pivotally movable relative to the body about a main pivot axis of the hinge means. The main axis is also suitable for moving in at least one guide slideway for guiding the main pivot axis in translation relative to the body in a direction that is substantially parallel to the longitudinal direction of the vehicle.