The new Mercedes-Benz E-Class - PART V


Stuttgart, Germany, Mar 03, 2009

Active safety: Warn, assist, act: over a dozen assistance systems to help prevent accidents

* ATTENTION ASSIST: drowsiness detection as standard

* Adaptive Highbeam Assist: ideal light in every driving situation

* Lane Tracking package: assistance systems to keep the car safely on track and ensure safe overtaking

* Speed Limit Assist: speed limit in force displayed in the cockpit

* DISTRONIC PLUS: radar-based proximity control and Brake Assist

* PRE-SAFE® Brake: autonomous emergency braking if there is an acute risk of an accident

* Aerodynamics: best drag coefficient in this vehicle class

Having achieved major advances in the field of occupant protection, Mercedes‑Benz is focussing more than ever on preventing traffic accidents and reducing accident severity as part of its commitment to road safety. To this end, the E-Class is equipped with tried-and-trusted technology in the shape of ABS, ESP® and Brake Assist as well as around a dozen new or modified driver assistance systems which are specially configured to help prevent frequent causes of accidents such as being too close to the vehicle in front, dangerous lane changes, excessive speed, drowsiness, darkness and lane departure.

This combination of safety technologies, which is unique in the world, make the E‑Class part of the "thinking" process – a car that is capable of seeing clearly, reacting instinctively and acting autonomously thanks to radar, cameras and

ATTENTION ASSIST, fitted as standard, even enables the new Mercedes Saloon to "feel": the system's highly sensitive sensors monitor the driver's behaviour and, based primarily on the steering wheel movements, detect when the driver is becoming drowsy. With this system, Mercedes-Benz is making a further contribution towards preventing accidents as, according to studies, around a quarter of all serious road accidents are caused by drowsy drivers – making drowsiness an even bigger cause of accidents than drink-driving.

The ATTENTION ASSIST system newly developed by Mercedes-Benz records over 70 parameters which are then assessed for the purpose of drowsiness detection. This continuous monitoring is crucial for detecting the floating transition from awakeness to drowsiness and for giving the driver plenty of warning.

Based on this wealth of data, ATTENTION ASSIST calculates an individual driver profile during the first few minutes of every trip. This profile is then compared with the current sensor data and the prevailing driving situation by the car's electronic control unit. In addition to the vehicle speed, lateral acceleration and longitudinal acceleration, the Mercedes system also detects use of the turn indicators and pedals as well as certain control inputs and external influences such as side winds or road unevenness, for example.

Steering behaviour a key indicator of drowsiness

Four years of development and testing work on the ATTENTION ASSIST system revealed steering behaviour to be an extremely meaningful indicator of drowsiness. In the tests involving over 670 drivers, the Mercedes scientists determined that drowsy drivers have trouble steering a precise course in their lane, making minor steering errors that are often corrected quickly and abruptly. This effect occurs at an early stage when drowsiness kicks in – often before the dangerous situation in which the driver falls asleep momentarily.

If the system detects drowsiness, it emits an audible warning signal and flashes up an unequivocal message on the display in the instrument cluster: "ATTENTION ASSIST. Break!"
ATTENTION ASSIST is fitted as standard in the new E-Class; it is active at speeds of between 80 and 180 km/h.

Light package: optimum light distribution in every driving situation

Driving a car at night will be even safer in future. Mercedes-Benz is unveiling an innovative system which adjusts the range of the headlamps automatically based on the distance to oncoming vehicles or moving vehicles in front of the car with their lights on. The system, called Adaptive Highbeam Assist, always selects the optimum headlamp range, allowing the driver to see the course of the road, pedestrians or danger spots at an earlier stage than would otherwise be possible.

Mercedes-Benz offers this new development as part of an optional package which also includes bi-xenon headlamps, the Intelligent Light System and LED daytime driving lights. In contrast to conventional systems, which merely switch between low beam and high beam, Adaptive Highbeam Assist controls the light distribution as the driving situation allows. The low-beam range can therefore be increased from around 65 to up to 300 metres – without dazzling other motorists. If the system detects oncoming vehicles or vehicles in front, it adapts the headlamp range continuously, based on the distance to these vehicles, so that the cone of light emitted by the headlamps ends before it reaches these vehicles. In addition, Adaptive Highbeam Assist takes into account the steering angle in order to dim the headlamps on tight bends. If the road ahead is clear, the system switches to high beam with a minimum of fuss.

Realistic tests confirm that motorists who use Adaptive Highbeam Assist are safer on the road in the dark: dummies placed at the side of the road to simulate pedestrians were detected from a distance of around 260 metres – around 150 metres earlier than is the case when conventional low beam is used – despite the presence of oncoming traffic. The new Mercedes assistance system therefore offers more than double the safety at night. What's more, it relieves driver stress as there is no longer any need to repeatedly flick the stalk on the steering wheel. So the driver can concentrate more on actually driving the car.

This innovative Mercedes technology is based on a camera, located on the inside of the windscreen, which monitors the traffic situation in front of the car. Thanks to an intelligent image-processing algorithm, the camera is able to detect other vehicles and the distance to them. The range of the variable-control bi-xenon headlamps is set based on these findings and adapted continuously depending on the distance to the vehicle in front or the oncoming traffic. The system operates at lightning speed, sending new data to the headlamps every 40 milliseconds.

Adaptive Highbeam Assist is ready to act at speeds above 55 km/h and operates autonomously once the driver has moved the rotary light switch to the "Auto" position and selected high beam using the multifunction stalk on the steering wheel.

Intelligent Light System with five light functions

As well as Adaptive Highbeam Assist, the Light package for the new E-Class includes the Intelligent Light System, whose five light functions are designed specifically for typical driving situations or weather conditions:

* Country mode
* Motorway mode
* Enhanced fog lamps
* Active light function
* Cornering light function

Low beam is replaced by country mode, which illuminates the driver's-side edge of the road more brightly and widely than before. In the dark, this enables the driver to appraise the situation more effectively and respond more rapidly when other road users cross their path.

At speeds above 90 km/h, motorway mode is activated automatically, increasing the driver's range of vision by up to 60 percent. This lighting function is activated in two stages: the Intelligent Light System first increases the output of the bi‑xenon bulbs from 35 to 38 watts, thereby increasing the light intensity and providing noticeably better illumination of the road ahead and the side verges. The second stage is triggered at 110 km/h, when the beam of the bi-xenon module on the driver’s side is elevated slightly. Motorway mode has a range of around 120 metres, and the driver is able to see about 50 metres further at the centre of this cone of light than is the case with conventional low-beam headlamps.

With the enhanced fog lamps, Mercedes-Benz improves driver orientation when visibility is poor. The new lighting function is activated at speeds below 70 km/h, as soon as the rear fog lamp is switched on. The variable headlamp technology incorporated in the Intelligent Light System makes it possible to pivot the bi‑xenon headlamp on the driver’s side outwards by eight degrees, while lowering the beam of light at the same time. This adjustment illuminates the inner half of the road more brightly and reduces the degree of glare from light reflected back by the fog.

The Intelligent Light System, part of the Light package, also includes the active light and cornering light functions. These are switched on automatically: depending on the steering angle, yaw rate and vehicle speed, the active light function pivots the headlamps sideways by up to 15 degrees almost instantaneously, thereby greatly enhancing illumination of the road. On an extended bend with a radius of 190 metres, this system enables the driver to see 25 metres further than is possible with conventional low-beam headlamps. This function operates in both low-beam and high-beam mode.

The cornering light function improves safety at crossroads, at T-junctions and on tight bends. It is activated automatically when the driver turns the steering wheel at a speed below 70 km/h. The headlamps then illuminate the area diagonally in front of the vehicle for a distance of around 30 metres, with a coverage angle of up to 65 degrees.

Standard features on the distinctive twin-headlamp face of the new E-Class include halogen headlamps. For low beam, the Mercedes engineers have developed a sophisticated projection system, which is housed in the two larger lamps. The inner headlamps, based on reflection technology, provide the high beam and serve as sidelights. Headlamp Assist, which switches on the headlamps automatically when it is raining, at dusk/dawn, in the dark and when entering a tunnel, is likewise specified as standard for the new E-Class.

Daytime driving lights: with LEDs as standard for the AVANTGARDE model

When it comes to road safety, being seen is as just as important as seeing – and not just at night. This is why the standard equipment package for the new E-Class includes daytime driving lights which switch on automatically when the engine is started. They are deactivated when the driver switches on low beam. E-Class AVANTGARDE models and models equipped with the Light package or Night View Assist PLUS feature daytime driving lights based on a total of 14 elegantly arranged LEDs which boast a very high light output but have a very low energy consumption of just ten watts. These are dimmed when low beam is switched on.

Mercedes-Benz also specifies LEDs as standard for the tail, brake and rear fog lights. One of the advantages of LEDs is their quick response, meaning that
drivers behind can be warned earlier when the brakes are applied in the event of danger. Like many modern Mercedes passenger cars, the new E-Class is fitted with adaptive brake lights, which flash four times as fast as the hazard warning lights during an emergency stop and, therefore, provide an extremely effective warning for drivers behind if a head-to-tail collision is imminent.

The combination of directly and indirectly emitting LEDs used for the tail lights ensures that the red sections of the tail lights, which are drawn deeply into the car's flanks, are illuminated homogeneously, while the indirectly emitting LEDs serve as background lighting and lend this light design its characteristic appearance. LEDs are also used for the indicators on the AVANTGARDE model or on models featuring the optional Light package or the Night View Assist PLUSsystem. The new E-Class can feature a total of up to 354 LEDs, depending on
the level of equipment specified.

Night View Assist PLUS with new function for highlighting pedestrians on the display

Mercedes-Benz has modified the familiar Night View Assist system from the S‑Class to include a special pedestrian-detection function. Hence the new name Night View Assist PLUS. As soon as the system detects pedestrians up to 90 metres ahead of the E-Class, they are highlighted by means of a frame with easily visible corners.
Night View Assist PLUSuses infrared technology to improve the driver's range of vision in the dark and when there is oncoming traffic: two separate headlamps illuminate the road with invisible and, therefore, non-reflective infrared light. A windscreen-mounted camera designed to pick up precisely this type of light records what happens in front of the car and sends the image to a display on the dashboard. The clear, needle-sharp greyscale image that appears here shows the scene in front of the car, allowing the driver to see pedestrians, cyclists or obstacles on the road at an early stage.

Lane Tracking package: a steering wheel that vibrates when the car leaves its lane unintentionally

The Lane Tracking package newly developed for the E-Class (available as an optional extra) incorporates two assistance systems which help the driver stay in lane and change lanes safely: Lane Keeping Assist and Blind Spot Assist.

The new Lane Keeping Assist system is based on a camera on the inside of the windscreen, which can detect road markings by evaluating the difference in contrast between the road surface and the markings. Based on this information, an electronic control unit determines the position of the E-Class and detects when the Saloon leaves its lane on the left or right.

Unlike conventional systems of this type, the Mercedes assistance system also assesses the driver's actions and, in so doing, can reliably ascertain whether the car has left its lane intentionally or unintentionally. There is therefore no warning if, for example, the driver accelerates before overtaking or joining a motorway, brakes heavily, or steers into a bend.

If Lane Keeping Assist detects that the E-Class is leaving its lane unintentionally, however, it activates an electric motor in the steering wheel, causing the steering wheel to vibrate briefly three times – a discreet yet highly effective way of prompting the driver to countersteer. The timing of the warning depends on the width of the road and the type of lane markings. If the car crosses over a continuous white line on the road, as opposed to a broken white line, the system emits its warning earlier. Lane Keeping Assist operates at speeds of between 60 and 250 km/h – as soon as the system has detected a lane marking.

Warning symbol in the exterior mirror if a dangerous lane change is attempted
The second Mercedes system in the Lane Tracking package, Blind Spot Assist, helps drivers to change lanes safely. It uses short-range radar sensors housed on both sides of the rear bumper to monitor the areas directly to the side of and behind the car. This process enables them to see if there is another vehicle in the adjacent lane – in the blind spot. In such situations at speeds above 30 km/h, the system informs the driver by illuminating a red warning triangle in the glass of the exterior mirror. If the driver fails to see this warning and indicates to change lanes, the warning triangle starts to flash and a warning signal sounds.

Speed Limit Assist: speed limit displayed in the instrument cluster

The newly developed Speed Limit Assist system (optional extra) reminds drivers of the speed limit currently in force by displaying it in the instrument cluster – a further contribution towards preventing accidents.

The image recorded by the windscreen-mounted camera, which monitors the area in front of the car on a permanent basis, is scanned for round surfaces only by an electronic control unit. These surfaces are then highlighted. In the next step, an algorithm filters out all objects that are round but do not resemble traffic signs. Finally, a comparison with stored patterns eliminates all but those objects which the system is programmed to detect: round traffic signs indicating the speed limit. The symbols are sent to the cockpit display, where they remain visible until the speed restriction is lifted or changed. The driver therefore remains fully aware of the current speed limit, enabling them to adjust the car's speed accordingly.

Thanks to the huge strides forward made in computer-based image-processing technology, Speed Limit Assist is able to work in real time, analysing the images within a fraction of a second so as to provide the driver with the required information practically instantaneously. Plus it makes no difference whether the speed-limit sign is at the side of the road or on a gantry above the road. The system is therefore able to react to variable speed limits (often indicated on gantries) as well as temporarily erected speed-limit signs, for example at road works.

Some of the speed-limit signs in Europe – for example those seen when entering or leaving towns in certain countries – are rectangular. In such cases, the assistance system also scans the data stored on the navigation system's digital map to check the plausibility of the camera image. The last speed limit detected disappears from the display in the instrument cluster when the car enters a built-up area, for example.

Driver Assistance package: radar systems to help prevent head-to-tail collisions

DISTRONIC PLUS and Brake Assist PLUS (optional extras) – Mercedes assistance systems based on sophisticated radar technology – are highly effective at helping to prevent accidents. This is one of the findings of an analysis carried out by Mercedes-Benz based on representative accident-research data. This technology can prevent a fifth of all head-to-tail crashes in Germany alone. On motorways, the accident rate can be reduced by as much as around 36 percent.Mercedes-Benz has further enhanced the radar technology for the new E-Class. The systems are part of the optionally available Driver Assistance package, which also includes the Lane Tracking package.

DISTRONIC PLUS proximity control operates at speeds of between 0 and 200 km/h: it keeps the car a set distance behind the vehicle in front, applies the brakes as required and can even bring the car to a complete halt, depending on the traffic situation. If the gap to the vehicle in front narrows too quickly, the system gives the driver an audible warning and, as soon as this first warning signal sounds, automatically calculates the brake pressure required to prevent a collision in this situation. This technology helps the driver to gauge the level of risk and, in combination with Brake Assist PLUS, makes the calculated brake boosting force available instantly, even if the driver does not press the brake pedal forcefully enough. Brake Assist PLUSallows controlled, targeted braking and, if necessary, increases the braking force right up to the point at which an emergency stop is performed, depending on the road speed and the distance to the vehicle in front.

Long-range radar with increased range and medium-range detection capability

When a potential accident situation is recognised, assistance is provided courtesy of two short-range radar sensors behind the front bumper and a long-range radar in the radiator grille. Mercedes-Benz has further enhanced the performance capability of these sensors: the new E-Class features a new long-range radar sensor with a range of 200 metres instead of 150 metres as previously. In addition, the sensor now also boasts medium-range detection capability, allowing monitoring of the area up to around 60 metres ahead of the car with a 60-degree beam width. This new technology enables even more accurate monitoring of the traffic situation and even better detection of dynamic events such as a car in front swerving suddenly. The two wide-beam short-range radar sensors with an 80‑degree beam width and a range of around 30 metres are still employed.

Automatic emergency braking provides an "electronic crumple zone"

Accident research shows that drivers do not always react as quickly as is necessary at critical moments – for example because they are distracted and therefore do not recognise the immediate threat of a head-to-tail crash, or because they fail to heed the warning signals given by an assistance system. The PRE‑SAFE® Brake, available as part of the optional Driver Assistance package, intervenes in situations such as these by braking the car automatically.

It does so in two stages: around 1.6 seconds before the calculated impact point – after three audible warning signals – the system initiates partial braking autonomously and decelerates the car with around 40 percent of the maximum braking power (approx four m/s²) as well as activating the reversible PRE-SAFE® occupant protection systems as a precaution.

Designed to supplement the visual and audible warnings, autonomous partial braking gives the driver a further, perceptible signal to act. If the driver then brakes immediately, the maximum braking force is made available or, if the driver swerves, the accident can be avoided at the last moment, depending on the driving situation. If the driver fails to react, however, even after automatic partial braking, the PRE-SAFE® Brake activates the maximum braking power around 0.6 seconds before the now unavoidable collision. This emergency braking can reduce the severity of the impact by a substantial margin.

Impact speed reduced by an average of 16 km/h

Realistic tests carried out by the Mercedes engineers have revealed that autonomous PRE-SAFE® braking reduces the impact speed by 16 km/h on average. The system therefore acts like an "electronic crumple zone", offering the car occupants even greater protection. The PRE-SAFE® Brake is active at speeds of between 30 and 200 km/h when moving vehicles are detected in front of the car. The system also reacts if the car approaches a stationary queue of traffic, providing its speed is below 70 km/h.

Parking aid: ultrasonic measurement of parking spaces

A newly developed system that can help drivers to park safely works on the basis of ultrasonic technology: sideways inclined sensors on the front bumper record the length of a parking space as the car drives past it (at a speed of up to 35 km/h), and indicate on the display whether the space is large enough to park in. After reverse gear has been engaged, instructions for safe parking appear on the display in the instrument cluster.

The tried-and-trusted Mercedes PARKTRONIC system (optional extra), which uses LEDs and audible signals to indicate the distance between the E-Class and an obstacle or another vehicle when parking, is also activated during this parking guidance to assist the driver. Mercedes‑Benz offers a further parking and manoeuvring aid in the shape of a reversing camera which films the area behind the Saloon and sends the image to the display in the instrument cluster.

The driver assistance systems for the new E-Class at a glance:

Aerodynamics: drag coefficient of 0.25 a new record in this vehicle category

Aerodynamics is becoming increasingly important as a development discipline as, in addition to being crucial with respect to safety, an ideal airflow around the vehicle has a major influence on fuel consumption (also see page 87) and noise levels. Mercedes-Benz therefore made aerodynamics a top priority when developing the new E-Class, employing state-of-the-art development and testing processes to further reduce aerodynamic drag, enhance active and perceptual safety, and improve aeroacoustics.

And the result is impressive to say the least: with a drag coefficient (cd figure) of 0.25, the new E-Class is the world's most aerodynamic standard-production saloon in this market segment, undercutting the already excellent figure achieved by the outgoing model (0.26) by four percent. The effect of the larger front end has been compensated for almost entirely, meaning that the cd x A figure for aerodynamic drag (drag coefficient multiplied by drag area) has only risen very slightly. The figures:

As in the case of safety developments, computer simulations are playing an increasingly key role when it comes to aerodynamics. Using a digital prototype, which provides a virtual simulation of the car right down to the last detail, the Mercedes engineers calculated the airflow around the Saloon very early on in the development phase – long before the first real prototypes of the new E-Class had been produced. This approach enabled them to use flow simulations to detect the potential for improvements at an early stage, meaning that the Saloon already displayed excellent aerodynamic characteristics when the subsequent "real" wind tunnel tests began.

Aerodynamic calculations of this kind require computers with exceptional processing power: in the case of the flow analyses performed on the digital prototype of the new E-Class, the computers had to crack differential equations comprising some 30 million fluid elements. Around 36 hours of calculation time on 64 processors are required until, finally, a realistic speed and pressure field appears on the computer monitor.

Hundreds of hours of wind tunnel work to optimise the details

Aerodynamic development involves a great deal of painstaking work and patience. The Mercedes engineers spent hundreds of hours in the wind tunnel, aerodynamically optimising detail after detail whilst at the same time striking an ideal compromise between form and function. Although each of the many individual measures often only resulted in an improvement of a few thousandths, their combined effects produced a highly impressive overall result, namely a drag coefficient of 0.25.

The rear of a car affects the drag coefficient even more than the front section, since the air swirl that can occur here acts like an invisible brake and increases fuel consumption unnecessarily. One of the ways in which the Mercedes experts prevent such air swirl is by incorporating a discreet, barely visible spoiler lip in the central area of the boot lid. In addition to this, they equip the tail-light lenses with special spoiler lips, which direct the airstream flowing along the car's flanks a long way rearwards; were these small spoiler lips not included, the air would flow inwards at the rear of the E-Class and create a vacuum, which would have a negative impact on both aerodynamic drag and lift.

Further aerodynamically effective details displayed by the new E-Class include:
Controllable fan shutter: allows the amount of cooling air to be limited as required, depending on the driving situation. Otherwise heavy pressure losses would occur as the air made its way into the engine compartment (also see page 87).
Aerodynamically optimised light-alloy wheels: reduce airflow separation and flow losses in the area of the wheels.

Sealed joints between the bonnet and headlamps: ensure an even better airflow around the front section.

Wheel spoilers on the front and rear wheels: improve the airflow around the tyres and reduce lift.

Cladding of the engine compartment and the underbody: optimises the flow of cooling air from the engine compartment and prevents flow losses caused by air blockage und swirl on the underbody.

Newly developed exterior mirror housing with triple benefits

The exterior mirrors on the new E-Class are yet another masterstroke on the part of the aerodynamics engineers. Right from the start, their aim was to develop a housing geometry that met specific requirements in three key areas: aerodynamics, aeroacoustics and safety. And they succeeded in this aim. Aerodynamically speaking, the shape of the mirror housings developed in the wind tunnel is so effective that the mirrors only account for around three percent of the body's total aerodynamic drag. This result can also be heard – or rather not heard – as the exterior mirrors have no effect on the body wind noise. During tests carried out in the aeroacoustics wind tunnel, the Mercedes engineers recorded the same levels on a test car without exterior mirrors as on the car fitted with the newly developed exterior mirrors.

Finally, the exterior mirrors also play a crucial role in terms of perceptual safety as they improve the driver's visibility when driving in the rain. The mirror housings are designed so that any rainwater hitting them flows outwards in a narrow groove running around the outside so that it can drip off at a precisely defined point. As a consequence, the side windows remain largely clean, affording the driver an unimpeded view of the exterior mirror and the outside. The A-pillars likewise help to keep dirt away from the side windows as they feature special water guides where the rainwater hitting the windscreen is collected before being blown downwards and across the roof by the airflow.

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