Abstract: The supporting members of a vehicle seat includes a molded plastic seat bottom support member and a molded plastic seat back support member. Cushion members for mounting on the support members include a cushion bun of resilient foam and a seat cover for enveloping the cushion bun. The seat cover has an opening in the underside thereof which permits insertion of the cushion bun when the cushion bun is compressed. A resilient retainer wire extends around the opening and is attached to the edges of the seat cover by J-shaped plastic hook strips so that the resilience of the foam bun exerts tension of the retainer wire. The retainer wire has a plurality of abutment structures integral therewith and adapted for mating engagement with corresponding abutments provided on the seat support members when the cushion member is forcibly stressed to flex the retainer wire.