A method for fastening parts or components, e. g. cables, tubes, conduits, hoses or the like to a portion of a body of an automobile by means of a plastic fastener, characterized by the following steps: forming a fastening hole in said portion of a blank body; inserting an adapter portion (10) into said hole, with said adapter portion (10)consisting of plastics which is adapted to resist higher temperatures, e. g. 180°C or more, without losing its shape,being substantially gastight within said hole;being mechanically secured in said hole against retracting forces by means of an undercut andhaving a head adapted to be connected to the head of a retaining portion of said part to be fastened through a snapping connection and connecting said head of said retaining portion with said head of said adapter portion after varnishing of said portion of said body.