Designing an open-top sports car with the structural stability and safety standards of a saloon calls for tremendous expertise and a great deal of experience. Mercedes-Benz has both of these attributes and the new SLK-Class is further testimony to this. The bodyshell of the sports roadster delivers superlative results in terms of strength and rigidity, the essential key to delivering dynamic driving characteristics combined with optimum vibration damping and Mercedes standards of occupant safety. The body also provides a robust base for the vario-roof with its sophisticated deployment mechanism, thereby allowing it to operate to very high standards of precision.
The figures speak for themselves:
- A measurement of the static bending strength on the body of the new SLK-Class reveals a 19 percent improvement with the roof down, when compared with its predecessor.
- Static torsional strength, an important indicator for the vibration characteristics of the body, outperforms the exemplary figures delivered by the previous SLK-Class by a remarkable 46 percent with the roof down.
These impressive results are due primarily to the adoption of two measures:
An intelligent choice of materials and an elaborate and costly body design process based on state-of-the-art calculation processes and a great deal of know-how.
Materials: 42 percent of all panels are made of high-tensile steel
When building the new SLK-Class, Mercedes engineers increased the proportion of high-tensile steel alloys to 42 percent of the total: these steels combine low weight with maximum strength, meaning that the great majority of components governing crash safety, strength and durability are now constructed from high-tensile sheet steel.
The specialists in the Sindelfingen plant also judiciously applied their tried and tested motto of using “the right material in the right place” to the use of other materials, wherever these delivered the greatest benefits and made the most significant contribution to the lightweight design concept. One such example is the curved rear panel, made of aluminium to deliver high strength combined with a substantial weight saving over a comparable component made of steel plate. This aluminium rear panel is bolted to the body. Mercedes-Benz selected pressure die-cast magnesium for the partition separating the fuel tank and the boot area, weighing about 50 percent less than steel would have done.
This demonstrates that the bodyshell of the new SLK-Class is a synthesis of high-tensile steel with lightweight aluminium and magnesium. The aluminium rear panel and the magnesium tank partition in the rear section of the roadster form a robust composite structure which not only saves weight but also makes a significant contri-bution towards body strength.
Fibre-reinforced plastic is used for manufacture of the entire fuel tank recess. This lightweight but remarkably strong high-tech material replaces the earlier steel variant and has already proven itself in this same location in the SL sports car. The oval flap over the fuel filler cap is also made of plastic, flipping open in response to fingertip pressure and snapping shut just as easily after the filling process.
Design: elaborate measures to achieve exemplary structural stability and safety
Mercedes engineers have also incorporated some clever new ideas in the develop-ment of this new SLK-Class, some intended to achieve superlative bending and torsional strength figures and some to achieve further improvements in occupant safety. These have enabled the specialists to build on the already high standard of the previous model by incorporating improvements to virtually every aspect of the bodyshell:
Front end structure
- The front cross member features an additional reinforcement plate to create a twin-shell design.
- The two straight longitudinal members are linked by means of special cross members which reinforce the front firewall area, assisted by two pedal base cross members.
- The curved firewall comprises several components. To counteract dif-ferent stress levels, these various sections feature different thick-nesses of material.
- The new design of the frame-shaped integral carrier for the steering unit, engine mountings and some of the wheel location components is intended to absorb energy in front-end collisions and is bolted to the front longitudinal members.
- The second and upper longitudinal member plane is connected to a strut secured to the A-pillars. This absorbs collision impact energy in the event of an offset front impact accident.
- The A-pillars are reinforced using oval tubes made of high-tensile steel. These are securely anchored to the body structure. The material is shaped in the steelworks while still in a semi-molten state, a process which makes the resultant component extremely strong. The oval shape of the A-pillars gives the SLK driver better all-round vision than in the previous model, an improvement quantified as twelve percent.
- The lateral longitudinal members comprise an inner and an outer shell section reinforced by transverse bulkhead panels. The cross sec-tion of these longitudinal members flares towards the back of the vehicle where additional, surface-mounted profile sections are fitted, enabling these members to contribute substantially towards the su-perlative rigidity of the vehicle body.
- The transmission tunnel, two straight connecting members on the underside which extend the front longitudinal members and two robust seat cross members constitute the reinforcing components of the floor pan assembly.
- The B-pillars (not shown) have substantial supporting faces against the lateral longitudinal members and the cross member under the aluminium rear panel.
- The rear longitudinal members on the SLK body are characterised by a multi-section design featuring different thicknesses of high-tensile steel. This approach has enabled engineers at Mercedes to define the strength and deformation properties of the longitudinal members very precisely, adapting each area to contend effectively with local stress loadings.
- The spare wheel recess is made of steel and forms part of the rear floor pan assembly.
- A robust cross member forms the rearmost rear component of the SLK bodyshell structure.
Four diagonal struts on the underside make a further important contribution to-wards the exemplary vibration damping characteristics of this roadster body. At the front end, they combine the integral carrier, which supports the engine mountings, the steering unit and some of the wheel location components, with the leading edge of the lateral longitudinal members. At the back end, these struts are connected at both sides to the longitudinal members and to an additional reinforcing member in the spare wheel recess.
The bonnet with its imposing front bulge around the Mercedes star, the characteristic identifying feature of the new SLK-Class, is also the result of innovative body and production techniques. Mercedes engineers developed a new process for manufacturing this good-looking one-piece bonnet section.
The frameless doors each consist of external panels with specially reinforced edges and an inner component comprising a sectional edge, an inner edging reinforcement and reinforcements on the hinges and lock together with a robust tubular section which supplements the numerous design features intended to protect occupants against side collision impacts. These side-mounted tubular members are arranged in such a way that they can also help to transmit the energy from frontal collisions to the rear body structure.
The opening action of the boot lid on the SLK-Class is fully integrated in the deployment sequence for the vario-roof and, by virtue of a twin-jointed hinge, is able to open in two different directions. A special technical feature of this boot lid is the two-section outer skin: the license plate recess – and this is a genuine first for Mercedes-Benz – is attached to the other panels on the boot lid using a laser brazing process. This laser process is so precise that the resultant brazed seam achieves a very high standard of quality.
Corrosion protection: fully galvanised body
To equip the SLK with long-term corrosion protection, the entire bodyshell is galvanised. In addition, some of the metal panels are treated to an additional organic coating on both sides which also contains rust-inhibiting zinc pigments. All the most vulnerable structural sections of the bodyshell are also protected with a cavity-fill preserving agent. A large area of the underbody is made from plastic so Mercedes engineers were able to dispense with conventional PVC underseal, a potential environmental hazard. The underbody trim panelling protects the bodyshell from stone chipping, wet and dirt. In keeping with all Mercedes passenger cars, the new SLK-Class is also protected by a 30-year MobiloLife warranty.
Paintwork: scratch-resistant clearcoat based on nano technology
This new type of clearcoat is derived from the nano-technology sector, providing a new and enhanced level of scratch resistance and also enabling Mercedes-Benz to take another important step along the road towards improving the already excellent durability and value retention of the SLK Class. This innovative paintwork system has been in service at Mercedes-Benz since the end of 2003, and the company was the first automotive manufacturer in the world to adopt it. This paint protection system is standard on the new sports roadster and is used with all the metallic and non-metallic paint colours for this vehicle.
Thanks to the impressive progress made in the nano-technology sector, engineers have been able to incorporate ceramic particles less than a millionth of a millimetre in size into the molecular structure of the paint bonding agent. To begin with, these tiny particles float freely around in the clearcoat while it is still in its liquid state, then group together during the drying process in the paintshop. At this point, the particles bond together to form a very dense, regular network structure on the surface of the paint. The nano particles improve scratch resistance by a factor of three and ensure a long-lasting and visibly improved gloss sheen on the paintwork.
This has been verified in a series of DIN-compliant standardised lustre measurements conducted in a mechanical laboratory car wash in which a precisely metered quantity of very fine quartz sand is added to the water. This enables the test to simulate the impact of repeated car wash visits within a very accelerated timeframe: depending on how dirty the car is at the time, ten of these laboratory wash cycles are the equivalent of between 50 and 100 car washes under normal conditions.
After the wash programme has finished, specialists use special lustre measuring equipment to examine the incidence of scratches on the painted metal panels and, at the same time, obtain a reading for what is referred to as residual lustre. The results are convincing: whereas the residual lustre reading obtained from conventional paintwork after ten washing cycles in this laboratory facility is typically in the region of 35 percent, the same number of cycles on scratch-resistant transparent nano paint will yield results in excess of 72 percent.
Vario-roof: new swivel mechanism creates more space in the boot
When it first appeared in 1996, the innovative vario-roof on the SLK-Class Roadster caused a sensation and set new trends in the construction of open-top cars. Mercedes-Benz has now developed this concept and has perfected the technology. The folding hardtop in the new SLK-Class now opens and closes even more rapidly than it did on the previous model. At the same time, a space-saving concept once again enables boot space to be increased when the roof is down.
Twenty-two seconds on a stopwatch clearly demonstrate that progress has been made. At the touch of a button, this is all the time it now takes to convert the new SLK-Class from a hardtop coupé to an open-top roadster, a whole three seconds faster than the previous model. Thanks to the ingenious roof design, the two-seater is able to change back just as quickly into a weatherproof, all-year-round car capable of meeting any of the everyday demands of road and weather. This means that the new SLK-Class is able to combine the driving pleasure of an open-top roadster with all the comfort of a Mercedes coupé.
Moreover, further development work on the new SLK-Class means that even more luggage space is available in the boot when the vario-roof is retracted. According to the VDA measurement method, the boot of this car offers 208 litres of stowage volume, an impressive 63 litres more than the previous model – quite enough for the luggage of both driver and passenger.
This great step forward was achieved by a new and highly elaborate roof design, the crowning glory of which is a swivel-mounted rear window – not dissimilar to the one in the SL-Class of sports car. This rotary movement ensures that the window nests firmly in the curved surface of the roof shell, restricting the capacity of the boot much less than in the previous model. Furthermore, a new luggage compartment cover prevents any collision from occurring between roof components and items of luggage when the roof is lowered. This robust luggage compartment cover replaces the roller cover used on the predecessor model and pivots longitudinally through a four-joint kinematic unit. The vario-roof cannot be opened unless this cover has been closed. In order to utilise the entire luggage space when the roof is closed, the cover can be folded forwards in one go.
The new vario-roof on the SLK-Class primarily comprises three elements connected together by an intelligent pivot mechanism: a twin-shell steel roof, the C-pillars with inner and outer sections and the rear window with its heated three-millimetre thick single sheet of safety glass. The intricate mechanism ensures that all roof components stow automatically in the upper area of the boot space whenever the roof is opened.
To allow this to happen, the boot lid is incorporated to form an integral part of the system. A tubular frame and additional hinges enable it to be pivoted in either of two directions: it can either open conventionally in the direction of travel to allow luggage to be loaded or unloaded. Alternatively, it can open in the opposite direction to enable the roof elements to stow away discretely. The refined kinematics employed on the vario-roof also include a generous, single-section rear shelf and two side flaps which neatly seal away and conceal the areas between roll-over bar, side panel and boot lid.
The highest standards of functionality and structural stability are assured by the support module for the vario-roof, formed primarily by an aluminium cross member bolted to the bodyshell structure. This supports the swivel mechanism for the right and left sides, the two roll-over bars and the hydraulic unit.
Sequence of movements: opening and closing in five stages
This creates a robust platform for a manoeuvre which nearly always elicits a fascinated response from anyone who witnesses it: whenever SLK-Class drivers press the switch on the centre console or activate the remote control on the optional comfort closing unit, a five-stage process commences. The intricate choreographic sequence which ensues can be viewed as a masterpiece of technology in motion.
- Stage 1: The catches on the roof frame are unlocked.
- Stage 2: The boot lid opens in the opposite direction to travel and the rear side windows are lowered. The front side windows (on the doors) each lower a few centimetres.
- Stage 3: The roof opens. The rear window rotates in the opposite direction to the rotary action of the C-pillars through an angle of approximately 150°. At the same time, the rear shelf swivels upwards.
- Stage 4: The roof element, rear window and C-pillars disappear into the boot where they nest closely together inside the curved surfaces of roof and rear window.
- Stage 5: The boot lid closes, then the rear shelf and side flaps merge shut to form a seamless surface. The front side windows then close completely again.
Five hydraulic cylinders are responsible for ensuring that the vario-roof on the new SLK-Class opens and closes smoothly. Two of these are in charge of powering the roof, one of them locks the roof centrally with two catches on the windscreen frame and the remaining two power the movement of the tubular frame. The multi-piston hydraulic pump with integrated electromagnetic valve is housed in the cross member behind the seats. It develops a pressure of 160 bar to ensure that sufficient power is available for all movements in any given situation. Limit switches monitor every sequence while a dashboard display panel on the multifunction instrument cluster advises the driver when the vario-roof reaches its fully open or its fully closed position.
Aerodynamics: Cd-value (drag coefficient) reduced by three percent
Good design, high standards of road safety, superb aerodynamics – this combination is by no means always a given in the compact roadster market. However, it is a distinctive hallmark of the Mercedes-Benz SLK-Class. Right from the days of the 1996 model, this car has combined captivating lines with a streamlined body shape, delivering benefits to fuel economy, ride comfort and roadholding.
Starting from what was already a very high standard, Mercedes engineers have managed to achieve even more progress with the new SLK-Class. Although the wider and higher body shape and the new tyre sizes (205/55 R 16 replacing the previous 205/60 R 15) have increased the total frontal area of the car by four percent to 1.93 square metres, the Cd value or coefficient of drag used to express the aerodynamic properties of a body shape have actually been reduced, when compared to the previous model, by three percent, achieving a new level of 0.32. Here is a summary of the measurement results:
The aerodynamic data for the new SLK-Class
Coefficient of drag Cd
Frontal area A m²
Wind resistance Cd x A m²
Even with the vario-roof open, the new SLK Roadster demonstrates that the aerody-namics engineers at the Sindelfingen plant have achieved their challenging objective: the Cd-value is now 0.37 compared with 0.38 on the previous model.
Aerodynamics is an engineering discipline influenced by many parameters, which is why the new SLK-Class features a wide range of detailed measures which combine to deliver the exemplary Cd-value of 0.32:
- Front and rear aprons: the aerodynamically styled shape of these attachments and the striking concave panelling along the sides of the body do more than sim-ply emphasise the dynamic character of the new sports roadster: they also have aerodynamic properties. They have the task of deflecting the flow of air across the front of the car to either side, thereby enabling the slipstream to pass over the car and to leave the car body at the back with minimum turbulence.
- Wheel spoilers: fitted to front and rear wheels, these small plastic components alleviate the air pressure which builds up in front of the tyres, thereby reducing the Cd-value while at the same time cutting down on lift.
Engine compartment trim: complete encapsulation of the engine compartment not only enhances acoustic comfort, i.e. noise levels, it also deflects the slip-stream to the rear and prevents air turbulence from developing in the engine compartment.
- Underbody panelling: the large, smooth plastic panels which extend right back to the rear axle enable the air to flow under the body without causing turbulence.
- Spoiler lip on the boot lid: this subtle detail improves the aerodynamic conditions as the slipstream leaves the back of the vehicle, reducing lift and minimis-ing the formation of turbulence.
- Exterior mirrors: the shape of these mirror housings was optimised in the wind tunnel.
Road safety: lift forces reduced by as much as 30 percent
With many of these aerodynamic details, the engineers in Sindelfingen were able to achieve two things at once: they not only reduced the coefficient of drag, they also improved roadholding at high road speeds or when braking, thereby making an important contribution towards road safety.
The underfloor panelling, wheel spoilers and spoiler lip on the boot lid help to cut down the airflow forces acting perpendicularly on the car, which quite literally cause the body to start lifting off the ground at high speed. However, the new SLK-Class keeps its feet firmly on the ground and displays superb roadholding manners at all times. This fact is verified by the data relating to lift, which demonstrate substantial improvements over the previous model – about 30 percent on the front axle and 20 percent on the rear axle.
The way the exterior mirrors, side windows and the rear window deflect dirt is a feature which contributes towards active safety and one which is therefore a high prior-ity for aerodynamic development engineers. Their aim is to guide rainwater up over the body or to deflect it down both sides while the car is moving, thereby ensuring that drivers retain good all-round visibility, even on long journeys in bad weather. The aerodynamically shaped housings on the exterior mirrors, the drain channels on the front roof pillars and special water ducts in front of the rear window all help to deliver this result, ensuring that the mirror surfaces, side windows and rear window on the SLK-Class remain almost entirely free of dirt when driving in heavy rain.
Driver and passenger comfort: effective measures to prevent draughts when driving with the roof down
The list of tasks presented to the aerodynamics engineers also included the heading of comfort. To be more precise, it specified the personal well-being and warmth of SLK occupants when driving with the vario-roof lowered. After all, given their many years of experience in the development of convertibles and roadsters, the specialists in Sindelfingen are perfectly aware of the fact that just being able to lower the roof of a car is by no means a reliable key to motoring pleasure. A cold wind which tousles your hair or sends cold draughts down the back of your neck can soon put a damper on the pleasures of open-top driving. To address this issue, the new SLK-Class has been tested and optimised in a wind tunnel. After an extensive series of in-depth studies, a new design of neck-level heating known as the AIRSCARF (an optional extra) is now celebrating its world premiere in this Mercedes Roadster.
However, AIRSCARF can only really come into its own if the other parameters are right as well – and one of the main issues here is that of draughts. This explains why the aerodynamic experts, when they began work on this product in the autumn of 1998, built 1 : 4 scale models to establish the basis for achieving perfect aerodynamics in the new SLK-Class. The angle of the windscreen and the seated height of the occupants were key aspects in this study right from the very outset because these are factors which play a key role in keeping the passenger compartment free of draughts. The result is a seat position carefully matched to the height of the windscreen which ensures that the slipstream is directed above the heads of SLK occupants. Their seats are therefore protected against wind, making the experience of driving much more comfortable. Measurements for temperature and air distribution across the occupants’ skin, recorded with the help of a “climate dummy” in the wind tunnel, have confirmed this fact. This is yet another area where the new SLK-Class outperforms its predecessor.
Even so, with the vario-roof down, it is not possible to completely prevent small pockets of turbulence from developing behind the occupants which can then prove to be a source of draughts. The answer to this problem is provided by the standard SLK draught-stop which is quick and easy to pull up over the two roll-over bars and which is then secured using press-stud fasteners. The closely-spaced mesh on this unit dis-tributes air very evenly, thereby preventing the kind of fast airflow which is experi-enced as draughts by car occupants. When used in conjunction with AIRSCARF, the air pacified by the draught-stop is then heated as well.
The SLK-Class also delivers comfort benefits in the form of improved aero-acoustics. With the vario-roof closed, noise levels inside the car are as low as those of a coupé. Moreover, additional aerodynamic measures also help to reduce wind noise – one example being the streamlined shapes of the side mirror housings.
Windscreen wipers: better performance, lower noise levels
The windscreen wipers are another development from wind tunnel testing, which helps to explain why these are officially designated as “aero wipers”: instead of the jointed bracket system of conventional wiper blades, to which rubber wipers are at-tached, the aero wiper comprises a one-part rubber profile with integrated spoiler and two curved spring rails which precisely match the convex curve of the windscreen and which therefore always make contact at an optimum pressure. The shape and 50 percent reduction in height of these blades deliver tangible improvements in wiper action and operating noise – especially at motorway speeds.
The new SLK-Class is equipped with a powerful dual-arm wiper system. The passenger-side windscreen wiper moves on a fixed rotational axis while its driver-side counterpart performs an additional lifting motion, thereby cleaning an even larger surface area of the windscreen. As an optional feature, the wiper speed can be controlled by a sensor on the windscreen which responds to the intensity of rainfall.
Lights: projection-type headlamps employing halogen or bi-xenon technology
The headlamps on the new SLK-Class are not only very appealing in visual terms, they also satisfy the highest standards in terms of their technology. Mercedes-Benz has now replaced its reflection-type low-beam headlamps with a new development known as the projection system. In this system, light is distributed by means of an optical lens (70 millimetres in diameter). As standard equipment, clear-glass H7 halogen lamps mounted behind plastic lenses provide low-beam lighting.
Stylistic considerations were not the only ones which prompted the company to move away from its previous reflector system. The projection-type headlamps certainly did not occupy as much space at the front of the vehicle as the earlier reflector-type units, and this was something which gave the designers much greater latitude in their work. Equally important however was the very apparent progress made in terms of lighting power: the projection technique offers much broader and much more uniform lighting of the road ahead and also delivers substantially greater range for the low-beam headlamps. Main-beam lighting is provided by additional reflection-type headlamps which also employ H7 halogen bulbs.
With the optional bi-xenon headlamps, the lighting output is even greater. Bi-xenon means that only one lamp is required for main-beam and low-beam headlamps: in contrast to main-beam lighting when the full light output is used, whenever low-beam is selected, a shutter is inserted between the lamp and the lens which obscures part of the beam of light. With bi-xenon headlamps on their main-beam setting, the H7 spotlights also come into play. To create a visual distinction between bi-xenon and halogen lights, the Mercedes designers have drawn a refined “eyelid” over the eyes of the new SLK. A transparent area above the bi-xenon module is backlit to create interesting light effects when viewed from the side.
A dynamic headlamp range adjustment unit automatically adapts the angle of the light beam to the prevailing body attitude and also compensates for brief dips and rises caused whenever the vehicle brakes or accelerates: this forms part of the optional bi-xenon equipment package for the new SLK-Class together with a headlamp cleaning system using high-pressure water jets. These same features can also be supplied as options on models fitted with the standard halogen headlamps.
No matter whether you choose halogen or bi-xenon – in both cases, the standard Headlamp Assist system will ensure that your lights switch on automatically when darkness falls or when you drive into a tunnel. The light sensor on the windscreen is also able to detect when either rain or snowfall is impairing visibility, responding to this by automatically switching on the low-beam headlamps, tail lights and licence plate lights. This function is activated by moving the lighting switch on the dashboard into its “Auto” position.
Cornering lights: fog lamps with an additional function
Fog lamps with halogen bulbs are also included in the standard equipment of the new SLK-Class. They are housed in the bumper trim and, in conjunction with the optional bi-xenon headlamps, also offer a new cornering light function. They are switched on automatically whenever the turn signal indicators are used or whenever the steering wheel is moved to a full-lock position, providing lighting for the area ahead and to one side of the vehicle. The advantage of this is that pedestrians and cyclists near the vehicle can be seen clearly, even at night. This cornering light function also enables drivers to orient themselves more effectively when cornering at low speed.
Through the development of this new cornering light function, Mercedes-Benz is demonstrating its ongoing development commitment to the principle of reality-based safety, and road accident statistics have indeed shown that the most serious acci-dents occur at night on intercity trunk roads and motorways. It also has to be said that the risk of being involved in a serious road traffic accident is much greater at night than it is during the day – despite the substantially reduced number of vehicles on the road at night. Pedestrians are particularly prone to risk, especially if they are walking to one side of a car turning towards them because the driver is often unable to spot them in time.
Whenever the bi-xenon headlamps are switched on, and up to the officially permitted maximum speed of 40 km/h, the cornering light functions cuts in automatically in re-sponse to the driver using the turn signal indicator or turning the steering wheel by a corresponding angle. At this point, the cornering light illuminates the area to one side of the vehicle to an angle of up to 65 degrees and a distance of up to 30 metres, thereby lighting up areas of the road which would normally not be visible with con-ventional headlamp technology.
Up-to-the-second information about visibility, road speed, steering angle and turn signal settings is communicated to the control unit for the cornering light by the car’s electronic data network: the control unit is a fully integrated component of this system. Based on this information, the micro-computer ensures that the correct cornering light function is delivered for a wide range of driving situations:
Crossroads are illuminated across a wide arc determined by turn signal indicator and steering wheel position. This also means that, when cornering, drivers are able to identify where the road is going well in advance and can then adapt driving style accordingly.
- On roundabouts the cornering light is determined by the turn signal indicator setting. This is because, while the steering wheel is typically turned one way while the indicator is set to the other, to show the direction in which the driver is leaving the roundabout.
- When reversing the electronic control unit bases its actions on the prevailing steering angle, but automatically inverts the switching logic in response: when re-versing with the steering wheel turned to the right, the system activates the left-hand low-beam headlamp and vice versa. This then ensures that the appropriate arc beside the vehicle is illuminated.
The intelligent electronic control unit does not switch the turning lights on or off abruptly: instead they fade in or out with a dimmer function. This operates more rapidly when fading in than when fading out. This gives the human eye time to adapt to a change in lighting conditions.
There is intelligence at work again in the design of the cornering lights. The design comprises a housing with a reflector and one H7 bulb per side. This skilful arrangement enables Mercedes-Benz to combine two lighting functions in a single housing: the halogen lamp in the cornering light also acts as a fog lamp.
Tail lights: the benefits of LED technology
Mercedes-Benz has also introduced leading-edge technology to the tail lights of the new SLK-Class: a grand total of 32 light-emitting diodes (LED) are responsible for brake lights and tail lights. Their field of light extends right across the full width of each tail light: when the brakes are applied, this red surface lights up to a substantially brighter intensity than it does for the tail light function.
Light-emitting diodes offer a range of benefits over conventional bulbs: they take up less space, offer a longer service life and light up much more rapidly when the brake pedal is depressed, thereby giving following traffic longer to react. This also explains why the third brake light, located on the boot lid of the new SLK-Class, is also equipped with LED lights.
The electronic databus networking – or multiplexing – on the new Mercedes roadster also makes possible a wide range of other lighting functions and switching options which enhance safety and comfort. Here are a few examples:
- Emergency lighting: in the event of a malfunction, a programmed circuit prevents complete failure of the front or rear vehicle lighting system.
- Daytime driving lights: using the multifunction steering wheel and the central display on the instrument cluster, drivers can programme the lighting system in their SLK-Class car in such a way that low-beam, parking, tail and licence plate lights come on automatically whenever the engine is started.
- Headlamp switch-off delay: If this function is programmed in using the multi-function steering wheel and central display, the fog lamps, parking lights, tail lights and license plate lights remain on after occupants have left the vehicle. This is intended to help them find their way in the dark. This lighting function can be set for any period of time between zero and 60 seconds.