If you brake abruptly, for example, the R-Class is already primed to respond thanks to its highly sensitive sensors. In the event of an accident, you receive enhanced protection at an earlier stage. PRE-SAFE® uses information from a number of systems, including the sensors of the Electronic Stability Program (ESP®) and Brake Assist (BAS). If a critical situation is identified, the driver and front-passenger seat belts can be tensioned in fractions of a second and the front-passenger seat adjusted to a more "favourable" crash position (only in conjunction with the optional memory package). If the system detects that a predefined lateral acceleration threshold has been exceeded, the sliding sunroof (if fitted) and side windows can also be closed. Once the danger has passed, belt tensioning is released and all other systems can be returned to the desired positions.