Abstract: A vehicle seat assembly having a support member extending laterally across the seat assembly and coupled to slide rails on each side forming a unitary frame structure movable upon fixed rails mounted to the motor vehicle. The unitary frame structure forms a platform upon which the seat cushion and seat back are mounted. By extending the unitary frame member outward beyond the sides of the seat cushion, the unitary frame structure can be mounted to the raised sill and tunnel of the vehicle body, above the floor. Alternatively, the unitary frame structure can be mounted vertically into the floor gaining the same benefits. This increases the space beneath the seat assembly which can be used by a rear seat occupant for his or her feet or for storage of other items.