A fastener for use in joining workpieces, for example automotive body parts such as a roof to a body frame member, is provided that includes a plastically deformable head portion, a platform disposed at a bottom of the head portion, and a distal end portion extending from the platform and defining at least one of elastically deformable locking member. The head portion is heat staked to one workpiece, and the elastically deformable locking member engages another workpiece to secure the workpieces together. The platform provides spacing, or a bond gap in one form, between the workpieces, and a material and geometry of the fastener are configured to compensate for a difference in thermal expansion of the workpieces.