Effects of car coating treatment on resistance to environmental corrosion and on cracks formed by collision were studied by microscopical, spectroscopical and mechanical methods. Treated and untreated samples aged for three years were used to examine the surface brightness, the water repellency and the crack appearance. From the results, it was verified that this excellent coating material mainly consists of silicone polymer and the treated car-body surface has resistance to corrosion and superelasticity.