Abstract: A selective opacity, maximally transverse retracting sunroof system for a vehicle roof is retrofitted to a vehicle by removing most of the original vehicle roof side rails and attaching thereto a strut assembly capable of supporting a self-contained sunroof mechanism to be attached thereto. The sunroof panel of the mechanism then is capable of covering the vehicle roof aperture from side rail-to-side rail. To decrease the undesired effects of a large, clear roof, the sunroof panel opacity may be chosen by the operator. Opacity of the panel is electrically controlled and provision is made for supplying power to the sunroof panel throughout its range of movement. A second, selective opacity roof panel may be used in the vehicle roof structure to maximize the light transmitting area of the roof.