Safety - at the root of all we do


Virtually no other area inspires the Mercedes-Benz engineers to produce such consistently impressive results as much as research into new safety technologies. The first important safety milestone was reached back in the 1950s with the development of the passenger safety cell, invented by Béla Barényi. Today it is just one of many components of the Integral Safety Concept which edges Mercedes-Benz vehicles ever closer to our vision of accident-free driving.

Phase 1: safe driving

For safe driving, the Mercedes-Benz safety concept supports you using many different measures: the control and display system is especially tailored to the driver. Then there are systems which are designed to alert and assist the driver in critical situations.

DISTRONIC PLUS proximity-controlled cruise control including PRE-SAFE® Brake (optional)[1]

DISTRONIC PLUS proximity control helps the driver to maintain a specified (timed) distance from the vehicle in front when travelling at speeds of 0 to 200 km/h.

With BAS PLUS Brake Assist in conjunction with the PRE-SAFE® brake system head-to-tail crashes can be prevented even more effectively. If the radar sensors detect there is a risk of crashing and the driver applies the brake, BAS PLUS is primed to apply braking in accordance with the situation.

If a potential collision is identified within the speed range 30 to 200 km/h and the driver fails to apply the brakes sufficiently early, the PRE-SAFE® brake system emits visual and audible signals. If the driver does not respond to this warning, independent partial braking is activated approx. 1.6 seconds before the calculated impact at a deceleration rate of up to 4 m/s2. If there is still no reaction from the driver, an independent full brake application can be initiated automatically 0.6 seconds before what is considered an unavoidable impact.

Adaptive brake lights

In critical braking situations, specific criteria such as brake pressure and road speed are used to activate the adaptive brake lights if necessary. When activated, the brake lights flash to give drivers behind even better warning of the risk of a rear-end collision.

Studies have shown that drivers’ brake-activation response times are shortened by up to 0.2 seconds when emergency braking is indicated by a flashing red warning signal instead of conventional brake lights. At a speed of 80 km/h, this reduction in response time corresponds to a reduction in stopping distance of approximately 4.40 metres. The brake lights flash with a frequency of approx. 3 Hertz (with bulbs) or approx. 5 Hertz (with LEDs). Tests have shown this frequency to be particularly effective.

As soon as the vehicle is moving at less than 10 km/h or has come to a stop, or Brake Assist is no longer active and vehicle deceleration falls below 6.5 m/s² for 150 milliseconds, the brake lights light continuously again.

The adaptive brake light comes on when:

  • the initial speed is greater than 50 km/h and Brake Assist BAS has recognised an emergency braking situation
  • the brake pressure is more than 75 percent of the maximum
  • As soon as the vehicle comes to a standstill, the hazard warning signal is automatically activated if the speed was more than 70 km/h before braking was initiated.

The ATTENTION ASSIST function is particularly helpful on long journeys and when driving at night; the system warns the driver if it detects signs of failing attention and increasing weariness.

ATTENTION ASSIST continuously analyses driving behaviour and steering movements. If the system detects certain steering patterns that frequently accompany drowsiness, it warns the driver visually by displaying the "coffee cup" symbol in the instrument cluster at the same time as emitting audible signals. ATTENTION ASSIST can be activated and deactivated in the main menu of the instrument cluster under "Assistance systems". When switched on, it is active at speeds between 80 and 180 km/h.

ADAPTIVE BRAKE with HOLD function, Hill-Start Assist and brake drying in wet conditions

The standard-fit ADAPTIVE BRAKE system improves ride comfort and safety by helping to perform critical braking manoeuvres more safely with the basic function of the ABS anti-lock braking system, while convenience functions support the driver in everyday driving situations.

  • Supportive HOLD function: activating the HOLD function of the ADAPTIVE BRAKE system by stepping on the brake pedal (depressing firmly) keeps the vehicle from rolling unintentionally when stopped at a light or in stop-and-go traffic.
  • Extra help: the Hill-Start Assist function prevents the vehicle from rolling back unexpectedly on inclines when moving from the brake to the accelerator pedal.
  • Full braking power without delay: the "brake drying" function removes the film of water that forms on the brake discs in wet conditions.
  • For an even quicker response: with the "Priming" option, the brake linings on the brake discs are primed as soon as the driver takes his foot off the accelerator quickly.
Intelligent Light System with LED daytime running lamps and cornering light function (optional)

The Intelligent Light System – as an active component of the safety concept – ensures the best possible visibility in all weather conditions and the most diverse traffic situations. In curves, fog or on free stretches of road the system adjusts to the situation by adapting the characteristics of the light individually.

Brings light to the darkness: in "country mode", the light from the low-beam headlamps is distributed in such a manner that the edge of the carriageway is significantly better illuminated than with conventional headlamps.

Increases dynamically: the motorway mode is automatically activated in two levels: from 90 km/h the system increases the output of the bi-xenon lamps. From 110 km/h the setting of the headlamp on the inside of the traffic lane also changes to uniformly illuminate the entire width of the lane for a distance of up to around 120 metres.

In extreme weather conditions: with the enhanced fog lamp function the system improves visibility when fog is present. The left-hand bi-xenon headlamp pivots outwards and the light cone is simultaneously lowered. This light function is automatically activated as soon as the rear fog lamp is switched on if the vehicle is not travelling faster than 70 km/h.

Follows the driver: the active light function follows the driver’s steering angle: sensor data on the steering angle, yaw rate and vehicle speed allow the bi-xenon headlamps to pivot to the side in fractions of a second as soon as the vehicle is steered into a bend. With the "cornering light" function the cornering lamps automatically switch on when the driver activates the indicator or turns the steering wheel. The Adaptive Highbeam Assist gives outstanding visibility at night as well, without dazzling oncoming traffic or vehicles ahead.

Helps improve the vehicle’s own visibility: the LED daytime driving lamps make it easier for other road users to spot the vehicle and the integral headlamp cleaning system minimises dirt build-up on the lights. In addition the front position lights and tail lights, the indicator lamp and licence plate lamp also use LEDs.

Phase 2: in critical situations

Mercedes-Benz stands for automotive safety. That's why our vehicles can help their passengers even in critical driving situations, so that every journey is as safe as it can possibly be.

PRE-SAFE® occupant protection system (optional)

The PRE-SAFE® preventive occupant protection system can recognise critical driving situations and, if necessary, pre-emptively activate reversible safety systems to help reduce the risk of injury to the vehicle occupants. To do this, PRE-SAFE® permanently monitors sensor data from systems such as the ESP® and BAS, and can thus, for example, recognise vehicle over/understeering as well as emergency braking.

If a typical critical driving situation is detected by the system, the electromotive belt tensioners can be activated, the passenger seat with a memory function can be moved to a better position for impact (only in conjunction with the optionally available Memory package) and the side windows can be closed automatically, all in fractions of a second.

Phase 3: in an accident

A host of safety systems work together in the SLK Roadster to prevent accidents. Should worst come to worst however, a number of different safety measures come into play. They include protection for the vehicle occupants as well as for other road users:

  • Protective core: The extremely rigid passenger cell and crumple zones ensure a high level of occupant safety. The reinforced A-pillar and the rollover bars also give the Roadster great structural strength.
  • Used when needed: depending on the type of accident registered, the seven airbags and belt systems can be selectively activated. The sensor system only activates the restraint systems that it calculates will be actually needed.
  • All-round protection: depending on the predicted severity of a collision, the adaptive front airbags in the SLK can be deployed in two stages (in a minor collision, in the first deployment stage the airbag is only partially filled). In side-on collisions exceeding a defined threshold, newly-developed head and sidebags in the flanks of the seat backrests are deployed on the impact side. The headbags deploy from the upper edge of the door inner sides, the sidebags are integrated on the outside edges of the seat backrests.
  • Safety is all in the head: crash-responsive head restraints improve occupant protection and help to reduce the risk of whiplash injury. In the event of a rear-end collision the head restraints are instantly displaced by around 40 millimeters towards the front and 30 millimeters upwards. This provides support for the seat occupants' heads at an earlier stage.
  • Intelligent protection for other road users: the standard active bonnet function can help reduce the risk of injury to pedestrians or cyclists colliding into the bonnet if the car is travelling at a speed between 25 and 55 km/h. To cushion the blow, the bonnet springs up by approx. 8.5 centimetres at the rear.
Active engine bonnet

The active bonnet can reduce the risk of injury to pedestrians and cyclists. If the system identifies a collision, the rear section of the active bonnet rises up by approximately 85 millimetres using spring force. This produces additional deformation space to absorb the impact energy of the upper body of the pedestrian/cyclist at an earlier stage.

Airbags for driver and front passenger

The airbags for the driver and co-driver provide protection for the occupants' head and torso in a collision, and also afford additional stability to the entire body. They are thus able to mitigate the severity of injuries sustained in an accident. If the crash sensors detect a collision, the airbags are deployed.

The gas generators of both airbags can be activated in two stages. Both stages are activated depending on the braking force applied. Depending on the predicted severity of the impact, the first stage of the gas generator is initially activated and the airbag only partially filled. If a higher severity of impact is predicted, the second stage of the gas generator is activated after a slight delay and the airbag is completely filled.

Headbags in the doors

The headbags in the doors can help protect the seat occupant's head and reduce the severity of possible injuries in the event of a side-on collision. If the crash sensors detect an impact from a certain direction and surpassing a predetermined intensity, the airbags are triggered. These airbags are deployed synchronously with the sidebags and on the side on which the impact occurs. When deployed, the headbag covers the side window and together with the sidebag offers optimum protection. Thus in the event of a side-on impact exceeding a predetermined level, the risk of head contact with the side of the vehicle or against intruding objects is reduced.

Sidebags in the seats

The sidebags for driver and passenger help to protect the body in the event of a side impact. They stabilise the entire upper body and can help to reduce the severity of injuries.

They are triggered if the crash sensors register acceleration or deceleration forces acting on the vehicle in excess of a specific threshold. The sidebags deploy at chest height between the side of the vehicle and the occupant.

Phase 4: after an accident

To reduce consequential damage after an accident and support the work of the rescue services, a number of different actions are initiated, depending on the type and severity of the accident:

  • Best possible protection: the engine can be turned off automatically and the fuel supply can be cut off.
  • Eye-catching lighting: hazard and emergency interior lights can activate automatically to lower the risk of accidents and help locate the car.
  • Better rescue possibilities: where necessary, side windows are lowered by a small amount and the doors can be automatically unlocked. Additionally, crash joints integrated between the wing and the door can make opening the doors after a frontal collision easier.
  • Direct connection: the Mercedes-Benz emergency call system (part of COMAND Online) can automatically make an emergency call through a connected mobile phone, as soon as the restraint system has recognised that an accident has occurred. It will communicate GPS positional data and other information to the Mercedes-Benz emergency call centre. It will then be possible to talk to the centre.

[1] Part of the optional Driving Assistance package[2] Part of the optional COMAND Online multimedia system[3] Standard equipment for the SLK 55 AMG; available as part of the optional Dynamic Handling package for all other models