Pre-Safe® fitted as standard on the M-Class, triggers preventative measures in the decisive moments before an accident occurs. If the sensors recognise an emergency braking situation or heavy over or understeering, Pre-Safe® ensures that the front seat belts are pulled taught by the belt tensioners 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). If over or understeering could lead to a roll-over, the sunroof (where fitted) is automatically closed.

When the danger has passed, the tension in the seat belts is released and the front passenger seat and sunroof can then be returned to their original position.