Using polycarbonate resin, which is an amorphous engineering thermoplastic, characterized by outstanding mechanical, optical, electrical and thermal properties, Volkswagen reportedly estimates a reduction in weight in previous all glass applications at 33%, while delivering a high-quality optical appearance and scratch-resistant surface.
The ability to create an aggressive curvature of the upper portion of the sidelite adds to form and function. Since the upper lite is polycarbonate and stationary there are no additional abrasion issues due to traveling between a door moldings or packaging issues with getting the glass in a confined opening like the door inner and outer envelope. The occupant will generally not depend on that area for general viewing.
Looking at the XL1's fixed and roll-down side windows pictured above, notice that the sidelite is two separate glass lites. The smaller of the two lites is glass and dynamic. The larger stationary lite is framed polycarbonate on its periphery to provide its structural integrity. This is because a polycarbonate side window will billow like a sail once the vehicle is mobile if not supported. The frame around the window adds rigidity, but also adds weight.
The requirements for plastic glazing are met by depositing plasma coating on the parts after molding. This glass-like plasma coating, applied over a hard coat, delivers enhanced weathering, durability, and abrasion performance and enables compliance with global requirements and regulations for plastic glazing applications.