According to BMW the flexible, stretchable, translucent,water-proof man-made fabric skin – polyurethane-coated spandex, is durable. It can handle high and low temperatures. The car changes its shape according to exterior conditions and speeds, and it also allows the person who is driving to change its shape at will.
The shape of the body is controlled by many hydraulic actuators, for example, the headlights are uncovered when small motors pull the fabric back in an eyelid like fashion. As the fabric is translucent the taillights shine through it.