4s maintenance records are written on the metal plate of the rear panel of the car. The tailgate of the car is the tailgate of the trunk, that is, the circle under the trunk, which is simply where the tailgate is located in the trunk. From the structural point of view, it is the inside of the rear bumper, above the junction of the rear floor, and the locking position of the trunk. Car rear-end collision is the most prone to collision. This is a metal plate, welded to the car. Automotive sheet metal means that automotive sheet metal is a processing method of automobile maintenance, also called cold working. If the appearance of the car body is damaged and deformed, the sheet metal process is needed. Automobile collision repair has developed from the initial smashing and welding repair to the secondary manufacturing and assembly of the car body. The repair of vehicles in a collision accident is no longer a simple automotive sheet metal knock, and the quality of repair can not be observed only by naked eyes.