Seven prizes and awards in just three years, together with praise and recognition from every quarter – that is the success story of PRE-SAFE®, the preventive occupant protection system. Mercedes-Benz first presented the system to the public in 2002, and since then PRE-SAFE® has proved its worth in more than 140,000 S-Class saloons.

The system is able to detect critical driving situations in advance and intervenes to prepare both the occupants and the vehicle for an impending collision. If the vehicle enters a skid or if the driver is forced to brake hard in an emergency, PRE-SAFE® tensions the front seat belts as a precaution, adjusts the front passenger seat to a favourable position and automatically closes the sliding sunroof if required. The position of the electrically adjustable, single rear seats is also improved. These preventive measures enable the seat belts and airbags to work more efficiently. If the accident is avoided, the preventive tensioning of the seat belt is automatically relaxed and the occupants are able to return the seats and sunroof to their previous positions. The system is then immediately ready to go into action again.

This early detection of accident-prone situations is based on a hitherto unique synergy of active and passive safety features. PRE-SAFE® is linked to standard handling safety systems such as Brake Assist (BAS) and the Electronic Stability Program (ESP®), whose sensors recognise potentially critical driving manoeuvres. This information is passed to an electronic control unit, which activates the preventive occupant protection system as soon as certain threshold values are exceeded.

Safety system: a combination of radar, Brake Assist and PRE-SAFE®

Three years after the world premiere of this trailblazing development, with which Mercedes-Benz began a new era in car safety, the second-generation PRE-SAFE® system is now entering series production in the S-Class. Mercedes engineers have improved the interaction between active and passive safety systems even further. This means that networking the radar-based Brake Assist PLUS system with PRE-SAFE® enables hazardous situations to be literally recognised in advance for even earlier activation of the preventive occupant protection features.

Accordingly the S-Class opens up new dimensions in car safety. No other automobile offers such a comprehensive safety system, which goes into action even before an impending accident.

While PRE-SAFE® previously responded to emergency or panic braking – i.e. after reflex-like operation of the brake pedal by the driver – the system in the new S-Class can also be activated if Brake Assist PLUS has used its radar system to predict an impending collision and a certain level of deceleration is exceeded when braking. The occupants are prepared for the potential collision by preventive tensioning of the front seat belts and repositioning of the seats (front passenger and rear seats), enabling the seat belts and airbags to give the best possible protection.

These well-proven PRE-SAFE® functions are enhanced with additional preventive measures in the new S-Class. This means that the occupants are even better prepared for an impending accident – always with the aim that the seat belts, belt tensioners and airbags can perform their functions perfectly during a crash:

Mercedes engineers have also made a further improvement to the standard windowbags with an additional preventive feature: if the new S-Class threatens to enter a skid with the probability of an accident, PRE-SAFE® automatically closes the side windows. These then support the windowbag as it deploys during a side impact or rollover. In addition, this new PRE-SAFE® function reduces the risk of the occupants being thrown out of the car or objects penetrating into the interior in the event of a crash.

Preview: PRE-SAFE® knee cushion for the front passenger

Mercedes-Benz will continue to develop preventive occupant protection features in the coming years. Future PRE-SAFE® concepts for even better preparation of the occupants when an accident threatens will for example include an automatically extending knee cushion which supports the front passenger and reduces impact loads on the legs during a crash. The knee cushion emerges from the lower section of the instrument panel before an impending collision, however its action is reversible, just like that of the PRE-SAFE® belt tensioners. The knee cushion is retracted once the danger of an accident recedes. On the same principle it might be conceivable to design interior door panels which move towards the occupants before a crash, keeping them away from body areas which might penetrate into the interior when an impact occurs. Extending B-pillar linings could fulfil similar support functions.

When PRE-SAFE® developers consider the future, they also imagine a protective system which is configured for the individual parameters of the car occupants. It might be conceivable for the driver and front passenger to programme the onboard computer with personal data such as their height, weight, gender and age before starting off, for example. This information would then enable the rate of inflation during airbag deployment, the force of the belt tensioners and the operation of the belt force limiters to be individually set. In addition it would be possible for PRE-SAFE® to control such things as the automatic seat positioning before an accident in accordance with the size of the occupant.