Abstract: An automobile bumper having an outer shape that forms a design surface. A mount is vibratorily welded to a back surface opposite to the design surface such that a fixture is fixed between the bumper body and the mount. The mount is melted by frictional vibration with the bumper body and so as to be integrally joined with that bumper body. Because the depth of the bumper body material being melted during vibrational welding does not reach the design surface, no shrinkages, uneven luster, welds or the like are produced on the design surface of the bumper body.

Abstract: The air spoiler includes a blow molded air spoiler body with a plurality of recesses molded in its lower wall and spaced from one another across the back of the automobile body. The recesses each have rising laterally opposite walls and in each recess a securement device is located which is fixed to the spoiler body by molding of the lower wall of the spoiler body. Each securement device can have a screw-threaded fastener threaded into it for securing the spoiler on the rear of the automobile body.

Abstract: In an air spoiler of wing type made of plastics material to be installed on the rear of a vehicle body, an air spoiler body is molded integrally with a mounting assisting member formed between an upper surface and a lower surface of the air spoiler body and along the longitudinal direction thereof. A mounting member, constructed separately, has one end joined to the rear, i.e. inner, side of the upper surface of the air spoiler body and has its other end locked to the mounting assisting member. The air spoiler is tightened by bolts to the vehicle through the mounting member. Accordingly, sink marks, such as may appear with an integrally-formed mounting member are not produced on the upper surface of the air spoiler body during the molding process and strain such as such as would be evident by causing the appearance of wavy forms on the upper surface at the installation state is reduced.