Saturn chose thermal plastic exterior body panels for their strategic advantage. The fenders and door outer panels are plastic exterior panels. Unique to this technology is the need to manage thermal expansion.

Thermal expansion allows exterior panels (e.g., fender, door, quarter) to grow and contract with changes in temperature. The method in which the exterior body polymer panels control this expansion is through a carefully engineered fastener system and exterior panel design. This movement on polymer panel travels in the forward and rearward direction in relation to the vehicle body side.

To allow this system to function, the fastener design consists of a steel shoulder bolt and plastic spring washer. This system allows for adequate compression of the joint for panel positioning and retention, yet allows the panel to slide along the slot for thermal growth.

To maintain functionality of this engineered growth management system, you MUST use and properly install the correct fasteners.