Depending on the type and severity of an accident, various measures can be taken to prevent further damage being caused in the aftermath of an accident and assist with the task of rescuing the occupants: the engine can be turned off automatically and the fuel supply cut off. In order to prevent a follow-on accident, and to facilitate finding the accident vehicle, the hazard warning lights and emergency interior lights can be automatically activated, and the side windows can also be partially lowered if necessary.

Various precautions have been taken to assist the work of the rescue team too. For example, the door locking mechanism can be released automatically after an accident. Crash joints between the wings and the doors can speed up rescue work by allowing the latter to be opened more easily after a frontal collision.

Even before a crash occurs, the M-Class can prepare for the impact: the standard PRE-SAFE? system triggers preventive measures in the decisive moments before an accident occurs. If the sensors recognise an emergency braking situation or heavy oversteer or understeer, PRE-SAFE? causes the front seat belts to be pulled taut by means of electric motors as a precaution and the front passenger seat is moved into a better position to cope with the impact (this function is only available in conjunction with the memory package). In driving situations with a high level of transversal dynamics indicating the vehicle is in imminent danger of a side-on collision or of overturning, the side windows and the sunroof (if fitted) are automatically closed. When the danger has passed, the tension in the seat belts is released. All the other components involved can then be returned to their original positions.