The front and rear ends of the car are equipped with bumpers (bumper), not only has a decorative function, more importantly, is to absorb and moderate the external impact, protection of the body to protect the body and the safety of the occupants of the safety features of the safety device.

Bumper has the role of safety protection, decorative vehicles and improve the aerodynamic characteristics of the vehicle. From the safety point of view, the car can play a buffer role in low-speed collisions, to protect the front and rear of the car body; in accidents with pedestrians can play a certain role in protecting the role of pedestrians. From the point of view of appearance, decorative, become an important part of the decorative sedan appearance; at the same time, the bumper also has a certain aerodynamic effect. At the same time, in order to reduce the sedan in the event of side collision injury to the occupants, in the sedan is usually installed on the door bumper, in order to enhance the door of the impact of the collision. This method is practical, simple, not much change to the body structure, has been widely used.

Installation of door bumpers is in each door of the door panels placed horizontally or diagonally several high-strength steel beams, play the role of the car before and after the role of the bumper to do the whole sedan before and after the left and right are bumper "escort" to form a "brick wall", so that the sedan occupants have a maximum security area. Of course, the installation of this door bumper for the car manufacturer, will undoubtedly increase the cost of some, but for the sedan passengers, safety and security will increase a lot.