The new Mercedes-Benz S-Class: Bodyshell and passive safety - Maximum stability and high-quality lightweight design

A high level of crash safety, lightweight design, outstanding rigidity for excellent handling with extremely low levels of noise and vibration. These were the aims when developing the bodyshell for the new S-Class. Application of the 3D Body Engineering approach has given it a third-generation aluminium hybrid bodyshell. The lightweight index – the torsional stiffness in relation to weight and vehicle size – has been improved by 50 percent compared to the predecessor model.

The bodyshell is the vehicle's functional backbone. All statutory, rating-relevant and internal crash load requirements are met, and even future requirements are already taken into account. To further improve suspension comfort, the shear forces acting at the force application points in the bodyshell had to be increased. These requirements were also met thanks to appropriate component design and special joining technology in the bodyshell. The lightweight index has been improved by 50 percent compared to the predecessor model. This index defines the torsional stiffness in relation to the vehicle's size (footprint) and weight. To this end, all the relevant node areas were optimised and systematically reinforced with respect to the force distribution.

The aim of the NVH measures for the bodyshell was to better the already very good preceding model with respect to vibration and noise comfort, but without dispensing with intelligent lightweight construction methods. The bodyshell structure of the new S-Class reaches new heights in dynamic rigidity thanks to new structural concepts and specific NVH measures in the bodyshell.

These include:

- Integral NVH front section concept consisting of extruded aluminium side members, cast aluminium elements at the transition between the front section and passenger cell, also at the damper domes, and integral carrier as vibration-damping structural component

- Increased use of bracing struts for specific increases in rigidity

- Rear panel and cockpit cross-member of hybrid metal/plastic construction

- Use of foam sections in the A/B/C-pillars to increase bodyshell rigidity

No weight increase in 20 years – despite stricter requirements

Since the 220 model series was developed in the 1990s, with an optimally coordinated materials mix the hybrid lightweight construction has been further developed into an aluminium hybrid bodyshell. During this period the share of aluminium has increased to more than 50 percent. It has therefore been possible to maintain practically the same body weight for 20 years and even slightly reduce it, despite far more stringent comfort and safety requirements and additional functions. In addition to this, structural foams are used at specific points in node areas in the new model series. The entire outer skin of the S-Class, including the roof and the front section of the body, consists of aluminium. The high percentage of aluminium is possible thanks to the use of the complete range of semi-finished products (cast, extruded and sheet aluminium). The safety passenger cell makes intensive use of high-strength steels.

This lightweight design by material and geometrical optimisation coupled with highly complex joining technology allows the new S-Class to further raise the bar in the demanding luxury saloon segment – without adding weight. With a torsional stiffness of 40.5 kN/degree (predecessor: 27.5 kN/degree), the S-Class achieves a new record in its segment.

Focus on driving dynamics: lightweight-construction measures

The front section is one of the preferred lightweight-construction zones for achieving balanced weight distribution of the entire vehicle. The decision to use aluminium as a lightweight material in this area was therefore made at an early stage. As well as being lighter than its steel counterpart, the aluminium front section also greatly enhances crash and NVH performance. Cast aluminium and extruded aluminium sections are used in addition to sheet aluminium. Die-cast aluminium was chosen for the shock absorber strut bracket because of its good integration properties. In this way it was possible to connect the front module without additional holders, for example. As well as reducing the number of components, die casting also enables the component to be designed to withstand specific loads and stresses. Morphological analyses were conducted to configure the wall thicknesses and geometry of the component so as to meet the strict functional requirements accurately.

In addition to local optimisation of the introduction rigidity at the shock absorber strut bracket and at the integral carrier, a cross-functional load path was conceived to further improve the system as a whole. The aluminium struts running in X-direction from the shock absorber strut bracket to the cowl provide support in the event of a crash. Supplemented by a multipiece framework, these struts also help to suppress the Y-movement of the side members. This design allowed the new load path to be incorporated into the limited package installation space in the front section. The forces are applied to the bodyshell structure in the three-piece cowl, which has been configured as a cast aluminium component in the centre section. In this case too, the casting allows a functionally perfect connection with distinct advantages in terms of weight and installation space.

The side members have been designed as combined aluminium extruded sections/castings to optimise crash performance, rigidity and component integration. The protrusions of the extruded aluminium sections of the side members required for package reasons have been designed to also have a positive effect on folding behaviour in the event of a crash. The cavity closed by a foam piece is also used as a resonance volume for the Frontbass system. The side members are connected to the steel passenger cell by means of cast aluminium components that allow a very rigid connection and integration of the integral carrier connection.

Clever combination: sophisticated steel and aluminium joining technology

The firewall area is a sheet steel construction. As well as meeting the functional requirements perfectly, this design also allowed integration of the complex hybrid joint between the aluminium front section and the steel cell. Here one of the major challenges was the mechanical joining technology used for the sophisticated high-strength steels.

In addition to the front section, the integral carriers are also made of aluminium and boast the lowest weight in their class. As well as acting as a component carrier for numerous components, the integral carrier is a central component of the front-end structure when it comes to performing crash and NVH functions. Compared to the previous model series, the complete cooling module is fastened to the integral carrier in addition to the engine, steering, torsion bar and front axle. The integral carrier's side members also form the third crash load path in the front section. In order to meet these multiple requirements yet still maintain a lightweight design, a complex aluminium mix comprising die castings/permanent mould castings, extruded sections and sheet metal parts was also required here.

The roof is another key area for lightweight design as reducing weight here has a positive effect on the vehicle's centre of gravity and on NVH characteristics. The new S-Class features an aluminium roof – a first at Mercedes-Benz. A major challenge here was integrating the roof into a steel structure. This was achieved by implementing an efficient and simple assembly solution in the bodyshop, which involves the roof being fixed to the bodyshell structure using shackles with defined spacing for the purpose of production in the factory. The resulting gap between the bodyshell structure and the roof ensures that the components are coated completely during the cathodic dip priming process.

One particular lightweight-construction measure involves the use of structural foam pieces in functionally critical node areas to ensure high NVH performance. Preliminary investigations have shown that comparable performance could only have been achieved by means of solid reinforcements, some of which would have required one-sided joining processes. Such reinforcements would have resulted in a double-figure increase in the bodyshell weight. Due to the way the foam pieces work, it is possible to position them precisely in the functionally critical node areas, since there is no need to take account of production-specific requirements such as joining technology limitations or component joining sequences. Furthermore, it is even possible to achieve frictional connections between cross-sections with several chambers.

Safety first: passenger cell made using high-strength steels

The safety passenger cell consists primarily of steel. Thanks to the use of higher steel grades, the weight has been kept the same as for the predecessor model although far more stringent crash requirements (angled mast) and stricter NVH requirements are met. All relevant components have been increased by one class in terms of material quality, one example being in the area of the B-pillar, roof frame and tunnel reinforcement, where thermoformed ultra-high-strength steels that have been weight-optimised as tailored products with different sheet thicknesses are used. In the lower side member area, an ultra-high-strength steel (CP 1000) is used as a roll-profiled component for the first time. This steel-based lightweight design by material optimisation is also backed by lightweight design by geometrical optimisation, including the formation of a frictional connection between the C-pillar and the rear centrepiece, which allows efficient support of the rear section's side members when the vehicle flexes.

In the case of detachable body parts such as the wings, bonnet and boot lid, the use of aluminium adopted for the previous model series was continued. The aim was to outperform internal and external competitors in terms of weight and to effectively implement the design in production whilst meeting strict requirements in terms of joins and seams. Proof that sophisticated design, lightweight construction and production-friendly product design can actually go hand in hand.

The aluminium hybrid design results in the use of additional mechanical joining technologies. The technical limits of the processes for these joining technologies were determined in collaboration with the supplier, the planning department and production. Consequently it was possible to combine high-strength sheet metal with aluminium for the first time and to reduce the sheet thickness of the components primarily from a functional standpoint. Only thanks to the interaction of lightweight-construction measures and lightweight-construction processes was it possible to make use of the 50 kg lightweight design potential. Conversely it was then possible to invest in a massive way in performance – in safety, comfort and customer benefit. Result: the bodyshell of the new S-Class is not only lighter, but also clearly tops in performance.

Restraint systems: meticulous design of every detail

Alongside the deformation potential of the body and major components, as well as the stability of the passenger cell, it is the quality of the restraint systems that largely determines the risk of injury to the occupants in the event of an accident.

The crash sensors, including appropriate software adaptation to detect the accident type and the collision severity, have been further refined compared to the predecessor model series. New components and features:

- STAR2 electronic control unit

- Pressure sensors for detecting collisions with pedestrians

- Use of sitting position information for adaptive control of the restraint systems

As standard, the driver and front passenger each have a three-point seat belt with triple pyrotechnic retractor tensioning. Retractor tensioning and belt force limiting as well as an electrically reversible inertia reel tensioner are effective via the shoulder belt. The upper belt guide point is anchored to the B-pillar and height-adjustable. The PRE-SAFE® Impulse tensioning system is a world first in the new S-Class (see "Extended PRE-SAFE® protection" section). The rear passengers in the two outer seats have three-point seat belts with inertia-reel tensioner and self-adaptive force limiter, while the centre seat features a standard three-point seat belt system. As optional extras, the seat belt buckle extender, beltbag and cushionbag elevate rear safety to a new level (see "Extended rear protection" section).

Driver and front passenger airbags: adaptive filling

The driver's airbag (volume approx. 64 litres) is equipped with a two-stage gas generator. Two stages can be activated, depending on the detected vehicle deceleration values, with a delay between triggering of the two stages. In addition to the two-stage gas generator, the front passenger's airbag (volume approx. 112 litres) has a special feature in the form of a pyrotechnically activated adaptive stage. The cushioning of the occupant when plunging into the airbag is made harder or softer depending on the sitting position and gas filling, according to requirements.

The thorax/pelvis sidebags for the driver and front passenger with a volume of 17 litres are integrated in the front seat backrests whilst the rear sidebags with a volume of 12 litres are integrated in the rear side panelling where they are firmly attached to the bodyshell. In the event of a crash, the windowbag cushion (volume approx. 40 litres) is filled by a hybrid gas generator that is located in the roof area behind the B-pillar. The use of a new weaving technology (X-Tether technology) makes the windowbag cushion more stable, meaning that it is easier to ensure effective inflation over a prolonged period of time.

Triggering of the side protection systems is controlled by the Star2 electronic triggering device, which can detect and assess a side collision with the help of a central acceleration sensor, additional satellite sensors in vehicle lateral direction and pressure sensors in the doors. Furthermore, the belt tensioners are triggered together with sidebags and windowbags if a side collision is detected and together with the windowbags if roll-over is detected.

Pedestrian protection: active bonnet and more deformation space

To supplement the active safety measures which help to prevent accidents or reduce the severity of accidents, the measures aimed at mitigating the consequences of accidents in the event of collisions with pedestrians have been further developed for the new S-Class. In order to reduce the loads exerted on a pedestrian if their head hits the bonnet of the vehicle, the deformation space between the bonnet and the components beneath it has been optimised. This is achieved in part by appropriate positioning of components such as control units or fluid reservoirs in the engine compartment.

The S-Class also features an active bonnet. In the event of a collision with a pedestrian, sophisticated sensors combined with intelligent algorithms trigger pyrotechnic actuators in the area of the bonnet hinges. These raise the bonnet by around 80 millimetres. The deformation characteristics of the bonnet have been developed specifically to meet these requirements. Further reductions in the impact loads can be achieved by using aluminium and by homogenously reinforcing the inside face of the bonnet. Furthermore, the hardness of the foam in the front bumper has been optimised to reduce the load exerted on the pedestrian's legs in the event of an impact.

Credits: Daimler AG

Copyright © 2013, Mercedes-Benz-Blog. All rights reserved.

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The new Mercedes-Benz E-Class 2013: Bodysheel construction and integrated safety concept

I. Body: Focusing on quality and functionality

The body of the E-Class has already proven its exceptional qualities when it comes to safety and comfort. On top of this it offers outstanding aerodynamics and, thanks to innovative production and quality assurance processes, consistently high quality. These characteristics impressed 400 automotive experts in 2009 when they presented the body of the E-Class Saloon with the EuroCarBody Award.

Since the basis of the body has not been changed, the new E-Class also boasts the same outstanding characteristics. These include:

- extremely stiff, rigid passenger cell made of highest grade steel
- high-strength steels
- comprehensive deformation zones in the front and rear areas
- lightweight construction - bonnet, wings and boot lid (tailgate on the Estate) are made of aluminium
- high ease of repair thanks to removable front and rear modules

Also new are the headlamps featuring LED technology – optionally also even available as full LED variants. The advantages of LED technology include:

- long service life
- colour temperature similar to daylight
- energy efficiency, since LEDs require significantly less energy than halogen and xenon lights while offering the same level of light output

HANDS-FREE ACCESS for convenient loading

Also new: as an option the E-Class can be fitted with so-called HANDS-FREE ACCESS in conjunction with the KEYLESS-GO package. Its state-of-the-art technology enables the boot lid to be opened and closed without actual physical contact by simply holding your foot beneath the bumper – a significant increase in convenience when loading and unloading the vehicle. The HANDS-FREE ACCESS feature also prevents hands from getting dirty and also luggage, since otherwise in the meantime one would have to place it down on the ground in order to open the boot.

The E-Class Saloon provides a spacious, illuminated boot. It has a volume of 540 litres, with space for four golf bags for example. The luggage compartment of the Estate is unrivalled in its spaciousness and sets the standard in this segment. Behind the rear seat backrests a volume of 695 litres is available, and with the rear seat backrests folded down this becomes up to 1950 litres. HANDS-FREE ACCESS, EASY-PACK Quickfold with convenience feature or the EASY-PACK folding folding load compartment floor with EASY-PACK luggage compartment comfort box all help to enhance the convenience and usability of the luggage compartment.

Consistent optimum values for aerodynamics and aeroacoustics

The outstanding aerodynamic qualities of the E-Class have also been retained following the design modifications implemented in the new E-Class. Both the Saloon (Cd value 0.26 - 0.28) and the Estate (Cd value 0.29 - 0.31) are at the top of their segment in this area too.

Excellent aeroacoustics effectively contribute to the typically high levels of ride comfort found in the E-Class. Even at high speeds, very little flow noise penetrates into the vehicle interior.

An additional increase in comfort can be achieved with the optionally available acoustic laminated safety glass for the sliding side windows in the front and rear. It creates even higher levels of noise comfort and at the same times affords more protection and safety against breakage.

II. New level of safety: Intelligent assistance systems with a keener eye

What started with the PRE-SAFE® system some ten years ago and continued with DISTRONIC PLUS has resulted in a new dimension of motoring at Mercedes-Benz: comfort and safety are merged into one, opening up all sorts of new prospects for motorists and car developers alike. Mercedes-Benz refers to this as "intelligent drive". Optionally, the E-Class features a whole host of new or optimised systems on board which help to make motoring more comfortable and safer.

In the main markets, the Saloon and Estate models are fitted as standard with COLLISION PREVENTION ASSIST, a radar-based collision warning system with brake assist systems. It helps to significantly reduce the risk of a rear-end collision. Also forming part of the standard equipment is ATTENTION ASSIST, which is now able to warn of inattentiveness and drowsiness across a wider speed range, and also inform the driver about his level of fatigue and the amount of driving time which has elapsed since the last break. It also offers an adjustable sensitivity level.

"The intelligent assistance systems of the future will be able to analyse complex situations and recognise potential dangers out on the road with the aid of improved environment sensor systems even more accurately than today," explains Prof. Dr Thomas Weber, Member of the Daimler Board of Management responsible for Group Research and Head of Mercedes-Benz Cars Development. "Figuratively speaking, the new E-Class doesn't just have eyes at the front, it has 360-degree all-round vision."

Of crucial importance in this respect is the networking of all systems, or "sensor fusion" as the safety experts call it. Mercedes-Benz is continually enhancing the performance capabilities of its assistance systems with the aim of ensuring comprehensive protection, not just for the occupants of a Mercedes-Benz, but for all other road users too.

The new systems hold tremendous potential for either preventing accidents or mitigating their consequences according to Dr Weber: "Take, for instance, the new BAS PLUS assistance system with Junction Assist. The results of our accident research based on the data from the GIDAS (German In-Depth Accident Study) indicate that it could reduce or prevent 27 percent of all accidents at road junctions resulting in personal injury. That equates to some 20,000 accidents a year in Germany alone."

New sensors, new senses, new intelligence

The basis for the innovative functions comes courtesy of highly modern sensors and appropriately networked algorithms. Mercedes-Benz is making a major leap forward with the introduction of the Stereo Multi-Purpose Camera (SMPC), or stereo camera for short. Just like the Multi-Purpose Camera (MPC) fitted previously, it is positioned behind the windscreen in the vicinity of the rear-view mirror. It has an aperture angle of 45 degrees and is capable of spatial detection of objects moving crossways ahead and also pedestrians, and calculating their path. The camera's two "eyes" provide it with a three-dimensional view of the area up to approx. 50 metres in front of the vehicle, and it is able to monitor the overall situation ahead for a range of up to 500 metres. In this way, the new camera is able to provide data for processing by various systems.

Intelligent algorithms evaluate this information in order to detect and carry out spatial classification of both vehicles that are driving ahead, oncoming or crossing, as well as pedestrians and a variety of traffic signs within a large field of vision.

Whereas the stereo camera's lenses act as the car's eyes, the radar sensors are its ears, so to speak, and provide additional data. The system of radar sensors comprises two short-range radar sensors in the front bumper with a range of 30 metres and a beam angle of 80 degrees, which are complemented by a long-range radar (200 metres, 18 degrees) including medium-range detection (60 metres, 60 degrees). The data from the camera and radars is amalgamated in a control unit in order to provide the system-specific data for the various functions.

Comfort-enhancing assistance with lateral lane guidance: DISTRONIC PLUS with Steering Assist

The DISTRONIC PLUS proximity control system is a driver aid designed to keep the vehicle at the desired distance from another vehicle in front that is travelling slower than the selected cruising speed. This basic radar-based function has now been enhanced by the addition of Steering Assist, which helps drivers to stay centred in their lane by generating the appropriate steering torque when travelling on a straight road and even on gentle bends.

The stereo camera recognises lane markings as well as vehicles driving ahead together with their spatial positioning, and relays this information to the electric steering assistance system. When driving at slow speeds, e.g. in congested traffic, the Steering Assist can use the vehicle ahead as a means of orientation, enabling semi-autonomous tailback tracking even when there are no clear lane markings visible. As a result, the system is able to further boost driving comfort and substantially ease the driver's workload in many traffic situations.

The new Steering Assist sub-function integrated into the DISTRONIC PLUS system is predominantly based on the new stereo camera. At the same time, the area in front of the vehicle continues to be monitored by two short-range radar sensors and a long-range radar sensor with medium-range detection. The system fuses the data gleaned from both technologies, calculates any reactions required, and then regulates the vehicle's linear speed as requirements dictate by controlling engine power, transmission and brakes, as well as actuating the electric steering for lateral vehicle guidance.

The DISTRONIC PLUS with Steering Assist can be activated as before with a selector lever on the steering wheel in a speed range from 0 - 200 km/h. Any speed between 30 km/h and 200 km/h can be selected as the desired cruising speed. A green steering wheel symbol appears in the instrument cluster to indicate when the Steering Assist is operating while DISTRONIC PLUS is activated. Meanwhile, linear controlling actions (cruise control function) continue to be visualised in the speed display by means of circular segments and the speedometer needle.

Drivers must keep their hands on the steering wheel at all times even when Steering Assist is activated, as the function only works in bends above a certain, speed-dependent radius. Legal considerations also mean there are no plans to introduce hands-free driving. The system's design is so refined that the sensors can detect whether the driver's hands are actually on the steering wheel. If they are not, a visual warning is issued first. Should the driver fail to react to this, a warning signal sounds and lateral lane guidance is deactivated. This does not affect the cruise control function, however, which continues to be operative.

Needless to say, the driver is able to override the Steering Assist at any time. If the driver signals to change lane, for instance, the lateral guidance function will switch into passive mode for the duration of the lane change.

The performance capabilities of the basic DISTRONIC PLUS function have been increased once again. Now, the system is able to brake at a rate of up to 5 m/s² without any intervention from the driver. If the "S" drive mode button is pressed, the rate of acceleration increases, too. Vehicle acceleration is also far more dynamic if the driver signals a wish to overtake by switching on the indicators, assuming the road is clear.

By combining the radar and camera data, DISTRONIC PLUS is also able to detect both vehicles cutting in and vehicles ahead in adjacent lanes and take any necessary action promptly. This can prevent illegal undertaking on motorways and similar multi-lane highways, for example, by adapting the speed to that of vehicles in the outside lanes.

Braking assistance for cross traffic too: BAS PLUS with Junction Assist

Apart from material damage, accidents at junctions often result in serious personal injuries, too. The new Brake Assist BAS PLUS with Cross-Traffic Assist from Mercedes-Benz is therefore capable of more than just helping the driver to avoid collisions with vehicles ahead or lessen their consequences in a purely linear direction: the new Junction Assist function can also come to the driver's aid when there is a risk of a collision with cross traffic at junctions.

If this anticipatory system detects a hazardous situation of this type, it prompts the driver to start emergency braking by activating visual and acoustic warnings. If the driver presses the brake pedal too tentatively, BAS PLUS will step in by automatically boosting brake pressure for effective emergency braking, even applying the brakes at full power if necessary. Applying just the right amount of braking power for the situation at hand maximises the available braking distance for traffic behind.

The Junction Assist function is operative at speeds up to around 72 km/h, while BAS PLUS is able to aid the driver in linear situations at any speed.

BAS PLUS with Junction Assist is potentially able to either prevent or lessen the severity of around 27 percent of all accidents at road junctions resulting in personal injury. This equates to some 20,000 accidents a year in Germany alone (source: investigations carried out by the GIDAS – German In-‑Depth Accident Study – and Mercedes-Benz Accident Research).

With pedestrian detection and city brake function: BAS PLUS and PRE-SAFE® Brake

Pedestrian detection has been added to the BAS PLUS and PRE-SAFE® Brake functions, while autonomous braking for vehicles in front has undergone a major enhancement too.

Thanks to the combination of stereo camera and radar sensors, it is now possible to detect pedestrians in front of the vehicle. Visual and acoustic warnings are triggered when a hazard is spotted. If the driver then reacts by braking, the braking power will be boosted by BAS PLUS as the situation requires, right up to a full brake application. Should the driver fail to react, PRE-‑SAFE® Brake triggers autonomous vehicle braking. The PRE-SAFE® Brake with pedestrian detection is active up to approx. 72 km/h, and is able to prevent collisions with pedestrians autonomously from an initial speed of up to 50 km/h.

Evaluations of GIDAS accident data indicate that this new technology could avoid six percent of pedestrian accidents and reduce the severity of a further 41 percent. The operating range of the autonomous braking function for stationary vehicles has been optimised so that rear-end collisions can likewise be avoided at speeds of up to 50 km/h.

BAS PLUS with Junction Assist and the PRE-SAFE® Brake with pedestrian detection rely on the same sensors employed for the adaptive proximity control system DISTRONIC PLUS with Steering Assist: the new stereo camera plus the multistage radar sensor system.

Reacts to broken lines too: Active Lane Keeping Assist

The new improved version of the Active Lane Keeping Assist is now also able to intervene should the driver inadvertently cross a broken line when the neighbouring lane is not clear and this could result in the risk of a collision when changing lane. The system can determine if this is the case using the information from the stereo camera and the radar system. The latter has been supplemented by a sensor at the rear, which works in unison with the other sensors in the front and rear bumpers.

The Active Lane Keeping Assist is not only capable of recognising critical situations such as overtaking vehicles, vehicles to be overtaken and parallel traffic, it can also respond effectively to oncoming traffic. If the system detects the vehicle crossing the lane markings when the adjacent lane is not clear, not only does it cause the steering wheel to vibrate in pulses as a tactile warning for the driver, it guides the vehicle back into lane by applying a corrective braking force on one side via the ESP®. It thereby forms the ideal complement to the Active Blind Spot Assist, and for the first time also enables the often fatal collisions with oncoming traffic to be avoided.

The Active Lane Keeping Assist is active at speeds between 60 and 200 km/h. If driver activity in the form of e.g. active steering, braking or acceleration is detected or when the indicators are switched on, both the warning and the corrective brake actuation are suppressed.

Now also identifies no-overtaking zones and no-entry signs: Traffic Sign Assist

A new Traffic Sign Assist which builds on the capabilities of the previous Speed Limit Assist represents yet another contribution to accident prevention from Mercedes-Benz. The system is now also able to recognise no-overtaking zones and alert drivers to no-entry restrictions.

The camera on the inside of the windscreen continues to pick up speed limit signs, including those on overhead gantries and in roadworks, for example. The camera's data is cross-referenced against the information in the navigation system and can be displayed in both the instrument cluster and the map view. If the camera fails to spot any road signs showing a speed limit or a speed limit is lifted, the legal speed limits based on the navigation data are shown instead, such as a maximum speed of 100 km/h on country roads in Germany or 50 km/h in built-up areas.

No-overtaking zones and the signs signalling their end are also registered and displayed, while in the case of signs imposing access restrictions, an acoustic warning is additionally emitted together with a visual warning in the instrument cluster – making an effective contribution towards helping to prevent serious accidents caused by wrong-way drivers.

Visualising drowsiness: ATTENTION ASSIST

A quarter of all motorway accidents in Germany are put down to drowsiness, making it one of the most frequent causes of accidents, most of which are of a serious nature. In 2009, Mercedes-Benz presented ATTENTION ASSIST, which is able to detect tell-tale signs of inattentiveness and increasing drowsiness based on changes in steering behaviour and a host of other factors.

The system has been subject to on-going development, and the latest version has the ability to detect drowsiness and inattentiveness across a far greater speed range from 60 - 200 km/h. Furthermore, the system's sensitivity can be adjusted, e.g. for drivers who already feel tired when they get behind the wheel.

A new menu in the instrument cluster display also makes the system more tangible and transparent for the driver by visualising the current attention level and the driving time since the last break. What's more, it is also possible to see whether the system is active in the current driving situation.

The system can be deactivated by making the appropriate selection in the instrument cluster menu. However, it will always be automatically reactivated with the sensitivity setting last selected the next time the vehicle is started.

Automatic manoeuvring into and out of parallel and end-on parking spaces: Active Parking Assist

The Active Parking Assist enables automated parking with active steering and brake control in both parallel and end-on spaces. It is an advanced version of the PARKTRONIC system with Parking Guidance offered previously. What's more, the system is now also able to manoeuvre out of parallel parking spaces again all by itself with automatic steering and brake control, assuming the vehicle was parked there automatically previously.

When travelling at speeds below 30 km/h, ultrasonic sensors with an extended range in the bumpers' side sections survey the nearside of the road for suitable parallel and end-on parking spaces. The same procedure is carried out for the far side of the road if the driver indicates accordingly. A symbol in the instrument cluster shows that the system is in the process of measuring. If a suitable parking spot is identified, an arrow appears alongside the symbol indicating that the system is ready for automatic parking. All the driver now has to do to activate the system is engage reverse gear and confirm by pressing the OK button on the steering wheel.

The Active Parking Assist steers and brakes the vehicle automatically as well as indicating the required driver actions in the display in each case, such as the transmission position to be selected. The driver moves the vehicle by lightly pressing the accelerator or releasing the brake.

Permanent high beam with no dazzling: Adaptive Highbeam Assist Plus

Around 20 percent of all road journeys in Germany are undertaken at night. But this is when some 40 percent of all accidents occur. A main cause for this is poor visibility. According to a study by the University of Michigan, high-beam headlamps can only be used during eight percent of driving time - which is nowhere near enough. Based on this, it can be assumed that the time during which high-beam headlamps can be used in Germany is likely to be even lower given the denser amounts of road traffic compared with the USA.

For the first time, the Adaptive Highbeam Assist Plus allows the high-beam headlamps to be kept on permanently while driving by masking out any other road user detected in the beams' cone of light. If the camera-based system registers either oncoming traffic or vehicles ahead, it will adapt the light distribution according to the specific situation when the high beam is switched on. Consequently, the driver can simply leave the high-beam headlamps on at all times and use their full range without irritating or even endangering other road users. There is no need to switch them on and off manually, resulting in a significant increase in the overall driving time with high beam.

The Adaptive Highbeam Assist Plus likewise makes use of the new stereo camera also employed by other assistance systems. If its image recognition algorithm picks up a vehicle that is oncoming or driving ahead, it actuates a mechanism in the headlamp module. This then masks the portion of the LED headlamp's high-beam cone of light where there are other vehicles to prevent their drivers from being dazzled. If road users are detected outside the area that can be masked – for instance when cornering with multiple vehicles in the headlamps' beams – the system will switch to the familiar system of headlamp range control using the low-beam headlamps.

Possible backglare caused by increased use of the high beam and highly reflective signs at the side of the road is also detected and eliminated by dimming the headlamps accordingly.

The Adaptive Highbeam Assist Plus builds on the Adaptive Highbeam Assist system first introduced by Mercedes-Benz in 2009. If this system detects oncoming traffic or traffic driving ahead with the help of a camera, it dips the headlamps and automatically adapts the low beam's range according to the situation. In this way, it allows the road to be illuminated for a long way ahead without dazzling other drivers. In addition to this, adaptive control of the low-beam headlamp range with smooth transitions results in gentler lighting changes that the eyes can quickly adjust to.

At a glance

The main new functions of Mercedes-Benz assistance systems

Comfort-oriented assistance

DISTRONIC PLUS with Steer Assist: helps with keeping the vehicle in its lane and tracks traffic in tailbacks

Safety - longitudinal guidance

BAS PLUS: can also detect crossing traffic and boost the braking power applied by the driver can detect pedestrians and boost the braking power applied by the driver

PRE-SAFE® Brake: can detect pedestrians, avoid collisions with pedestrians or stationary traffic at up to 50 km/h by means of autonomous braking and reduce the consequences of a collision at up to 72 km/h

Safety - towards the rear

PRE-SAFE® PLUS: can detect imminent rear-end collisions, trigger PRE-SAFE® occupant protection measures in an imminent rear-end collision, firmly apply the brakes of the stationary vehicle in a rear-end collision to reduce the forces to which occupants are subjected and to avoid secondary collisions

Safety - lateral guidance

Active Lane Keeping Assist: can detect oncoming traffic and if the adjacent lane is occupied, and prevent the vehicle from leaving its lane unintentionally by applying the brakes on one side

Safety - at night

Adaptive Highbeam Assist Plus: allows the high-beam headlamps to be kepton permanently without dazzling traffic by masking out other vehicles in the beams' cone of light

Safety - when parking

Active Parking Assist: enables automated parking in both parallel and end-on spaces with automatic steering and brake control enables automatic manoeuvring out of parallel parking spaces

Driver's level of attention and condition

ATTENTION ASSIST: can warn of lack of attention and drowsiness in an extended speed range of 60 to 200 km/h. can provide the driver with information on his level of fatigue and the amount of driving time which has elapsed since the last break provides an adjustable sensitivity level

III. Trend-setting safety: Airbags, restraint systems and pedestrian protection

Innovative driver assistance systems, preventive protective measures, a stress-resistant body structure and highly effective restraint systems make the E-Class one of the safest vehicles in its segment.

The basis for this is the integrated safety concept from Mercedes-Benz, which combines all elements of active and passive safety in a well-thought-out system – providing protection to the vehicle occupants and other road users. The integrated safety concept meets, to an unprecedented extent, the requirements for a high degree of vehicle and road safety, and is oriented towards real-world accidents.

PRE-SAFE® PLUS: occupant protection in an impending rear-end collision

Mercedes-Benz has extended the well-known PRE-SAFE® preventive occupant protection system to cover dangerous situations caused by traffic following behind.

A radar sensor in the rear bumper monitors the traffic behind the vehicle and can detect an impending rear-end collision. The system alerts the driver of the vehicle behind to a dangerous situation by quickly flashing the rear hazard lights (not for the USA and Canada). In addition, it triggers the preventive PRE-SAFE® occupant protection measures, which include reversible belt tensioners and active NECK-PRO® head restraints.

If the vehicle is stationary, PRE-SAFE® PLUS will keep it firmly braked, thus reducing any forward jolt. This can greatly reduce the strain placed on the occupants and the risk of whiplash injuries, for example. Firmly applying the vehicle's brakes can help to prevent secondary accidents too, such as running into a vehicle in front, for example, or colliding with pedestrians or other road users at junctions.

State-of-the-art restraint systems

In the event of an accident, the best possible protection is provided by the restraint systems, the comprehensive deployment of airbags and the structural safety of the body. An innovative sensor system triggers the safety systems depending on the situation and coordinates them all with each other.

Restraint systems are the backbone of passive safety.

- 3-point seat belts for driver and front passenger with electronic, reversible belt tensioners in the PRE-SAFE® phase and pyrotechnic belt tensioners in the event of an accident as well as belt force limiters.
- 3-point seat belts on the outer seats in the rear with pyrotechnic belt tensioners, belt force limiters for all rear seats and rear belt status display in the instrument cluster. Making up part of the optionally available Rear Seat Safety package are 3-point seat belts with self-adaptive belt force limiters on the outer rear seats, which are able to adjust the belt force for small passengers and children in particular.
- NECK-PRO head restraints for driver and front passenger which provide early support for the head in the event of a rear-end collision and as such are able to reduce the risk of whiplash.
- ISOFIX child seat anchor points on the outer rear seats for the safe attachment of appropriate child seats with additional respective anchor point above on the rear seat backrest.

Also fitted on board the E-Class is an elaborate system of airbags:

- adaptive airbags for driver and front passenger with multistage deployment, depending on the detected severity of the impact
- sidebags for driver and front passenger, which are able to provide additional protection in the event of a side impact
- pelvisbags for driver and front passenger, which are able to protect the pelvic area in the event of a side impact
- windowbags between the A, B and C-pillars, to protect the head area of the driver, front passenger and passengers seated on the outer rear seats
- kneebags, which in specific types of impact can protect the driver in the area of the dashboard which comes into contact with the knees, and also stabilise the entire upper body by positively influencing occupant movement in the event of an impact
- sidebags in the rear provide additional protection for passengers on the outer rear seats; they are part of the Rear Seat Safety package which is available as an optional extra

Also making a contribution to safety is automatic child seat recognition (ACSR). It can deactivate the airbag on the front passenger side when a child seat with a corresponding transponder is fitted.

Consistent pedestrian protection

The E-Class also plays an exemplary role when it comes to pedestrian protection. The following measures are implemented for pedestrian protection:

- active bonnet, which is moved upwards by 50 mm when an impact is detected, thus creating additional deformation space during the impact; the system is reversible and can be reset by the driver, without having to visit the workshop, to enable him to continue driving
- BAS PLUS warns when pedestrians are detected in the danger zone by the Stereo Multi-Purpose Camera. The PRE-SAFE® Brake with pedestrian protection triggers autonomous braking when the system detects a pedestrian in the danger zone and the driver is not reacting to the system's warnings. This pedestrian detection, in conjunction with the optionally available Driver Assistance package Plus, represents a milestone in preventing accidents with pedestrians and/or reducing their consequences.

Credits: Daimler AG

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