- Mercedes-Benz SLK350, 2012
The 2012 SLK-Class unites premium comfort and high-quality equipment with an especially athletic flair. At the same time the new roadster is the most fuel efficient in its class matched with segment-leading safety. All-weather driving enjoyment - open or closed, during weekends or the daily commute - is built-in to the SLK's genes. The 2012 Mercedes-Benz SLK350 goes on-sale in the U.S. in June 2011.
Outstanding on all fronts
The best or nothing - this motto is at the heart of the Mercedes-Benz philosophy, and also the guiding theme for the new SLK. From the start the roadster was designed to provide top performance in all areas, and Mercedes-Benz engineers have rigorously translated this requirement into reality giving the SLK attributes that provide the roadster with a peak position in its segment. Among them are extremely compact dimensions combined with a generous interior with numerous practical features. Outstanding performance and sporty, agile handling are also major characteristics of the new SLK. The new SLK is also the safest roadster with its unrivalled range of safety features.
Striking, athletic and stylish
The designers have tailor-made a body for the new SLK that emphasizes its classic roadster proportions. Behind the long hood is a compact passenger compartment and a short rear overhang - key attributes that characterize all the classic roadsters from Mercedes-Benz.
Striking front end
The first eye-catching feature is an upright radiator grille that bears the new Mercedes-Benz brand look. The grille emphasizes the long and well-proportioned hood, and with its light-catching contours it already hints at the roadster's dramatic qualities. The wide radiator grille bears the Mercedes-Benz star in a prominent central position and displays a powerfully contoured chromed fin at the front. The clearly defined headlamps complete the look of the new SLK's face and resemble that of the legendary 190SL from the 1950s, which is regarded by many as being the original "SLK". However, the designers did not just focus on the past; with the new SLK's front end they also intentionally created a close visual link with the new Mercedes-Benz SLS AMG "gullwing" and the new CLS-Class.
The impressive result of this meticulously detailed work is that in spite of the more striking, steeper front and larger frontal area, the Cd value has been cut to just 0.30 - a brilliant achievement (the predecessor model's Cd value was 0.32).
Dramatic lines
The timeless, classic shape of the side profile with the classic roadster proportions embodies aesthetics of the highest caliber and is a visual cue to the vehicle's sportiness and driving pleasure. Fine details show the care that has been taken by the Mercedes-Benz designers. For example, a molding conceals the trunk joint, so that the side line doesn't interfere, as it usually does with similar roof designs. The ventilation grilles in the front fenders with a chromed fin are reminiscent of the famous Mercedes-Benz roadsters of the 1950s. In the new SLK, they form the perfect starting point for a feature line, which flows to the muscular rear fender, using light and shadow to add style and timeless aesthetics to the sides. Meanwhile, the upper edge of the wide headlamps - which for the first time feature LED technology - also appears to flow into the feature line.
The line is emphasized by the stemmed exterior mirrors, which are positioned on the beltline where they allow a better forward view to the side with their very narrow stems painted in the vehicle color. Their sophisticated aerodynamics also helps to keep the side windows practically dirt-free, while ensuring a low level of wind noise.
Muscular rear end
At the rear, the eye is drawn to the integrated spoiler lip and wide tail light clusters. For the first time, the tail lights with their pronounced horizontal design are in all-LED technology. Their upper edge extends forward into the sides, culminating in the feature line. A twin exhaust system with trapezoidal tailpipes rounds off the muscular impression.
Premium materials and stylish sportiness
Despite the most compact dimensions in its class, the 2012 SLK has generous interior dimensions. To achieve this, the designers have developed interior appointments that offer the driver and passenger the highest degree of quality and precision. The interior is characterized by stylish sportiness and genuine high-quality materials which have been manufactured with perfect precision and skilled craftsmanship. Standard brushed aluminum trim covers the center console; wood trim can be ordered as an option in high-gloss dark brown burl walnut. Four round, metallic air outlets integrated in the dashboard emphasize that this model truly belongs to the Mercedes-Benz sports car family, their shape being a nod to those in the SLS AMG.
Echoing the exterior design, the black dashboard emphasizes the horizontal lines and width of the vehicle. The SLK's generous round dials flank a display for the onboard computer. The color display for the communications and entertainment functions is housed in the center console and is easily read by both the driver and passenger.
An ergonomic multifunction sports steering wheel with a flattened bottom and thick leather rim makes the high quality and athletic character of the new SLK a constant tactile experience. Shift paddles and metal trim on the spokes add both sportiness and refinement. The interior can be enhanced even further with the Trim package which includes a wood/leather steering wheel and shift knob.
The sweeping lines of the upper dashboard section are continued into the door panels. The center panel of the door is color-coordinated with the interior and the door pulls and seat adjustment switches are trimmed in aluminum or optional wood.
Sporty yet comfortable seats
The sporty, ergonomic seats with adjustable crash-responsive NECK-PRO head restraints integrated into the backrests have high side bolsters for optimum lateral support and comfort on long journeys. Convenience and seating comfort is provided by electric seat adjustment with memory functions and 4-way lumbar support.
The Mercedes-Benz SLK350 offers a choice of Black, Sahara Beige or Ash sun-reflecting leather as well as Black and Bengal Red Premium sun-reflecting leather which noticeably reduces heat build-up. The leather has a special coating which reflects the sun's rays and measurements have shown that this reduces the temperature of the seats by more than 18 degrees Fahrenheit - a significant improvement in comfort when the car has been parked in the sun.
As in the previous model, the neck-level heating system AIRSCARF is available as an optional extra for the new SLK. This creates a flow of warm air around the neck and shoulder areas of the occupants from a vent in the front of each head restraint.
Attractive lighting
An ambient lighting system available for the first time as an option in the Sport Package creates an impressive effect in the interior of the new SLK. It consists of discreet optical fibers in SOLAR RED, which produce a pleasant yet dramatic lighting effect in the door panels, around the door pulls and on both sides of the center console. This mood-enhancing ambient lighting is activated when the doors are opened ("welcome home" effect), and its intensity can be individually varied by a dimmer.
The central interior lights are located in the overhead control panel and includes two interior lights and a center console spotlight. Additionally, a single LED is located in each A-pillar to provide extra interior illumination on entry and exit.
Clever storage compartment concept
The new SLK offers an exemplary variety of storage options to provide versatility and day-to-day utility. The glove compartment has been enlarged by 26% in comparison with the previous model. In addition, the glove compartment lid includes useful features such as holders for a pen, credit cards and coins.
There are three storage compartments in the center console - below the air conditioning controls, dual cupholders next to the COMAND controller on the center console and under the center armrest with a 12 V socket, USB interface and AUX connection (optionally a media interface for integration of an iPod is available as part of the Premium 1 Package). A net attached to the tunnel in the passenger footwell is fitted with a flexible bottle-holder which can securely accommodate even 50 fl. oz. bottles.
Excellent climate
The new SLK is equipped with a windshield defogging sensor in the stem of the rear-view mirror which registers the glass temperature and interior humidity level of the new SLK. In dry weather, when no cooling is required but the A/C is operating, the control system powers the compressor down but activates it as soon as it detects that the windshield is fogging-up. This has two advantages:
- The A/C function can remain active all the time, but the demand-controlled system saves energy.
- As the air conditioning only demoisturizes and cools as much air as is required to maintain the interior temperature, the air is never too dry to detract from the comfort of the occupants.
Innovative technology with a unique roof
Driving a roadster is a very emotional experience, conjuring images of cruising through the countryside with the sounds and smells of the outdoors, the top down and the sun shining. Rainy weather doesn't have much impact since the SLK-Class has always a retractable hard-top which converts the roadster into a coupe with a fixed roof at the touch of a button. Mercedes-Benz engineers have constantly refined the hard-top and maintained the SLK's pioneering role in this technology.
Unique equipment: MAGIC SKY CONTROL
For the first time Mercedes-Benz is offering a choice of three variants of the lightweight-construction retractable hard-top for the new SLK:
The standard roof is painted in the vehicle color.
Optionally available is a panorama roof with dark-tinted glass.
The third option is a world premiere - the panorama roof with MAGIC SKY CONTROL. This glass roof switches to light or dark transparency at the press of a button. In light mode it is virtually transparent, offering an open-air experience even in cold weather. In its dark state the roof provides welcome shade and prevents the interior from heating up from the sun's rays. In other words: a comfortable atmosphere at the touch of a button.
The operating principle is based on the physics of a plate condenser: if the glass structure is subjected to an electrical voltage, particles in the structure position themselves so that light is able to pass through the glass. If the voltage remains switched off, however, the particles position themselves randomly. This partially blocks the light, and the glass remains dark. The control unit and converter are integrated into the front section of the roof, and the switch is in the overhead control console.
UV and infrared light are also effectively blocked in transparent mode, while insulation increases even more significantly and noticeably in darkened mode, thereby helping to keep the temperature on interior parts such as armrests cooler by up to 18 degrees Fahrenheit compared with conventional tinted glass.
Measurements using a device called a star pyranometer in Death Valley, one of the world's hottest places, impressively demonstrated the effect. This device measures the intensity of exposure to sunlight. With an open roof, the thermal load from the sun in the heat of Death Valley reached 1000 to 1100 W per square meter. With the transparent glass roof it dropped to 200 W, and when the roof was switched to darkened mode with MAGIC SKY CONTROL, it dropped to 40 to 50 W - one 20th of the original value and less than a 60 watt bulb.
Since the innovative glass also shields against the sun's rays far more effectively than conventional thermal insulation glass or sunblinds, the occupants of the new SLK also enjoy the highest level of climatic comfort. When driving with the roof open would be unpleasant due to intense heat, the driver and front passenger are able to relax under the MAGIC SKY CONTROL roof - an important contribution to onboard comfort and the driver-fitness safety typical of a Mercedes. Even when the vehicle is parked the interior does not overheat since the roof is switched to darkened mode when the ignition is turned-off.
MAGIC SKY CONTROL not only benefits passengers but also the environment as some of the strain is taken off the air-conditioning system, thereby saving on CO2 emissions.
In addition, the frame of the three roof variants is now of magnesium. This makes each roof around 13 lbs. lighter than in the previous model, giving the car a lower center of gravity.
The engineers have also refined the operating mechanism for the roof and trunk lid. It now takes less than 20 seconds to open or close the roof completely. The improved mechanism also creates more trunk capacity.
Fully suitable trunk for everyday use
The luggage capacity with the retractable hardtop closed is 10.1 cubic feet. A golf bag or a large suitcase is also no problem.
When the roof is opened the capacity is reduced to 6.4 cubic feet, sufficient space for two large sports bags, for example with tennis equipment.
To prevent luggage from colliding with the roof components there is a luggage cover in the trunk which can be pivoted longitudinally. The roof can only be opened if this cover is pivoted to the rear, and when the roof is closed the cover can be easily pivoted forward by hand to facilitate loading and unloading, and makes the full trunk capacity available.
Bodyshell structure with aluminum components
The bodyshell structure already proved highly successful in the preceding model, and was weight-optimized still further for the new SLK. Accordingly the hood and front fenders are made of aluminum for the first time, as are the dashboard cross-members and the rear end; the rear bulkhead module is made of fiber-reinforced plastic. The torsional rigidity of this optimized lightweight steel construction was improved even further thanks to the intelligent use of lightweight construction methods, reducing the bodyshell weight by around 29 pounds.
The doors are completely new, with reinforcement at the beltline and at the lower edge. A section of high-strength steel ensures excellent side impact protection. The well-proven A-pillars with welded-in oval tubes of hot-formed ultra-high-strength steel and a robust nodular connection to the side members remain unchanged.
To keep repair costs down, the front side members have a prescribed cutting point for a sectional repair, and their shape causes them to bend ahead of this area in the event of a collision.
Exemplary aerodynamics
In addition to familiar features such as a spoiler lip on the upper edge of the trunk lid, wheel spoilers in front of the wheels, and full engine compartment and underbody cladding, the newly designed exterior mirrors and painstaking modifications to the A-pillar cladding contributed to the excellent drag coefficient.
The A-pillar cladding is a good example of meticulous development work. It took more than one year to develop a plastic cover that would combine strict design requirements with proper functionality. The result is a pillar cover with a fine front edge and a drainage channel on the upper surface. This ensures a very close airflow and therefore a significant reduction in air resistance, drafts, aeroacoustics and soiling of the exterior mirrors and side windows.
AIRGUIDE: Innovative windstop system
A comfortable alternative to the conventional windstop is the new pivoting AIRGUIDE which has been invented by Mercedes-Benz aerodynamics engineers. It consists of pivoting transparent plastic shields which are attached to the roll bars. This is the world's first windstop that enables different comfort levels to be selected by the two occupants. The driver and passenger can individually pivot the units to the center of the vehicle in an instant and tame turbulent air flow without any installation or removal effort.
Modern headlamp technology and LED daytime running lamps
The Mercedes-Benz SLK350 is equipped with horizontally arranged LED daytime running lamps with four LEDs. The new SLK can be optionally equipped with the Lighting Package which provides active and cornering light functions.
The active headlamp includes intuitive headlamp range control which automatically adjusts the angle of the light beam to changes in the car's attitude - for example pitching movements when braking and accelerating - or to accommodate changes in vehicle loading.
The wide tail lights of the new SLK feature full-LED technology for the first time. This not only ensures an unmistakable nighttime design, but also enables LEDs to shine with different intensities in specific areas of the tail light cluster, depending on their lighting function. LED technology has other advantages: compared to conventional bulbs they light up around 0.15 seconds faster, and also have a considerably longer operating life.
Athletic spirit and ecological efficiency
The 2012 SLK350 is powered by a redesigned direct-injection V6 engine developing 302 hp/273 lb-ft. of torque from its 3,498 cubic-centimeter displacement, using this power to accelerate in 5.4 (est.) seconds from 0 to 60 mph (top speed 155 mph). Its fuel consumption is estimated at 20 city/29 hwy mpg thanks to its 3rd-generation direct injection, piezo injectors and multi-spark ignition.
Launching later on in the model year, the SLK250 goes on-sale with a turbocharged four-cylinder direct-injection engine developing 201 hp/229 lb-ft of torque from a displacement of 1,796 cubic centimeters. The SLK250 is equipped with a standard 6-speed manual transmission and consumes an estimated 23 city/31 hwy mpg. From a standstill it reaches 60 mph in 6.5 seconds, and it has a top speed of 155 mph.
New V6 engine with innovative technology
The six-cylinder engine is part of the new V6 family of efficient direct injection engines. Known as BlueDIRECT, this innovation establishes the V-engines from Mercedes-Benz as worldwide benchmarks and makes a further reduction in fuel consumption by 20 percent possible by engine modifications alone.
The V-angle of the new V6 engine is only 60 degrees. This enables the balance shaft for primary vibrations to be omitted. As a result, the driver notices a high level of comfort. The crankcase, pistons and cylinder heads of the V6 are made of aluminum while the crankshaft, connecting rods and valves are built from special forged steel.
The technology in the new engine generation includes a number of new developments that are unique in combination:
- Multi-spark ignition and third-generation spray-guided direct fuel injection system with piezo-electric injectors that offer more fuel savings through a homogenous combustion process with a considerably extended characteristic map and fuel-efficient lean-burn technology.
- Power consumption by auxiliary units has been reduced. These include an optimized water pump with 2nd-generation thermal management, a demand-controlled oil pump, a volume-controlled high-pressure fuel pump and an intelligent generator management system.
Lightweight construction techniques and detailed improvements have also reduced in-engine friction considerably compared to the previous engine.
Third-generation direct-injection system
Spray-guided direct gasoline injection (which Mercedes-Benz was the first car manufacturer to introduce in series production) is now in its third generation. The system pressure is up to 2,901 psi and is variably optimized according to the engine's performance. New piezo-electric injectors allow up to five injections per intake stroke for the best possible mixture formation.
The crystalline structure of the piezo-ceramic changes in microseconds under an electric voltage and with the precision of just a few thousandths of a millimeter. The central component of a piezo-electric injector is the piezo-stack, which directly controls the metering needle. With a response time of just 0.1 milliseconds, the fuel injection can be very sensitively and precisely adjusted to the current load and engine speed, with a beneficial effect on emissions, fuel consumption and combustion noise.
In the V6 motor, the multiple injections even in tiny quantities made possible with piezo-electric injection technology were used by Mercedes-Benz engineers to control a wider, usable combustion process with efficient lean-burn operation.
Multi-spark ignition for optimal efficiency
The third-generation direct injection system also features rapid multi-spark ignition (MSI). Following the first spark discharge and a brief combustion period, the coil is rapidly recharged and a second spark is discharged. The MSI system enables up to four sparks to be discharged in rapid succession within one millisecond, creating a plasma with a larger spatial expansion than conventional ignition. Controlling this rapid multi-spark ignition enables both the time lapse before the next spark and the combustion duration to be optimally adjusted. This provides versatility in optimizing the center of combustion and improving residual gas compatibility, especially during stratified charge operation. Fuel consumption can be reduced by roughly two percent this way.
Fuel savings of up to 4 percent are possible alone by the use of piezo-electric injection technology in combination with multi-spark ignition, depending on the driving cycle.
Cylinder head with new camshaft adjuster
Mercedes-Benz engineers modified the variable, hydraulic vane-type camshaft adjusters for the intake and exhaust sides by using the basic architecture of the preceding engine. These now have a larger adjustment range of 40 degrees with reference to the crankshaft. Engineers were also able to improve the functionality, achieving a 35 percent greater adjustment speed and adjustability at an oil pressure as low as 5.8 psi. Despite the improved performance, this new component features significantly smaller dimensions and low weight. For this reason the installation space on the longitudinal and vertical axes of the engine was able to be reduced by around 0.6 inches.
Two-stage chain drive for low noise
The extreme compactness of the camshaft adjusters was achieved by the new, two-stage chain drive. A primary chain drives two secondary chains - one per cylinder bank -via an intermediate gear. All three chains can be individually adjusted via a chain tensioner. This results in low tensioning forces and low chain dynamics, ensuring consistent timing and outstanding acoustic properties, with friction reduced even further. In short, the new chain drive is compact and provides low-noise operation.
Exhaust system for stringent emission standards
The exhaust systems for the SLK were developed to meet the ULEV exhaust emission standards as well as noise emission standards. The exhaust system for the 4-cylinder engine consists of a firewall catalytic converter, a center muffler and two rear mufflers.
The emission control system for the V6 gasoline engine has a firewall catalytic converter for the right and left cylinder banks. The exhaust gases then flow into storage-type NOx catalytic converters. These are followed by a twin-pipe center muffler and rear mufflers designed as reflection/absorption mufflers on the left and right and rounded-off by two exhaust tailpipes.
Four-cylinder with a bite
The four-cylinder engine for the new SLK250 follows the downsizing principle with the reduced cubic capacity compensated by homogeneous direct injection and turbocharging. This leads to advantages such as lower weight and reduced engine friction. A smaller engine also moves the operating range of the combustion process towards more favorable conditions with consequent fuel consumption improvements.
The direct injection system of the four-cylinder engine has an injection pressure of up to 2,031 psi. In the interests of improved efficiency, this allows the compression ratio to be increased versus a conventional port injection system. The fuel evaporating directly in the combustion chamber also lowers the temperature in the combustion chamber, reducing the engine's tendency to knock. The engine is homogeneously charged.
Turbine rotors are used to generate charge pressure in the four-cylinder engine. The single-flow turbocharging of the four-cylinder engine operates more efficiently than a mechanical charger since no engine power needs to be devoted to the rotors.
Other characteristics of the four-cylinder engine include four-valve arrangement with forged intake and exhaust camshafts, as well as camshaft adjustment on the vane-cell principle. This enables the valve timing to be rapidly and variably adjusted. The result is high torque even at low engine speeds, and a higher specific output.
The crankcase and cylinder head are cast from aluminum alloy. The crankshaft is also cast, and has eight counterweights. To compensate the secondary masses inherent to a four-cylinder in-line engine, two Lanchester balancer shafts rotate within the crankcase at twice the crankshaft speed.
An electronically controlled thermostat provides controlled engine warm-up (no coolant flows through the cylinder head when the engine is cold), and therefore intelligent thermal management and shortened warm-up phase.
Sporty exhaust note
A sporty exhaust note produced by a new sound generator provides an acoustic backdrop to the 4-cylinder SLK250. This generator is located immediately in front of the throttle flap, and enhances the exhaust note with elements of the intake noise. It filters out certain frequencies from the intake noise and conducts them into the vehicle interior via a pipe connection - an ingeniously simple and very effective solution for a sporty and appealing engine sound.
Automatic transmission with fuel economy benefits
The improved seven-speed automatic transmission is standard equipment for the Mercedes-Benz SLK350 (optionally available on the SLK250). The transmission has undergone extensive further development to achieve decreased torque converter slip, a significant reduction in internal losses and optimized efficiency. Mercedes-Benz developers reduced vibration in the transmission by incorporating a new torsion damper which makes low speed operation more comfortable.
ECO mode reduces engine speeds and considerably improves fuel economy (up to seven percent) but also provides an even faster response to accelerator movements. A new hydraulic circuit and optimized torque converter mapping also contribute to better acceleration. Further fuel economy measures include a new transmission fluid with a lower viscosity and longer service life.
The optimized electrohydraulic control unit of the transmission and new reduced-friction materials in various parts of the transmission in combination with optimized software result in improved shifting comfort.
The closest connection to the road
It is the suspension that establishes contact with the road, and ride comfort and agile handling depend on it. The new Mercedes-Benz SLK offers a choice of two versions:
A lowered sports suspension with harder springs and dampers ensures a systematically sporty driving experience
An optional Dynamic Handling package is available as a special order option. Its merits include a suspension with continuous adjustable damping. It has an electronically controlled fully automatic damping system, so the vehicle rolls away gently even on poor road surfaces, but still offers high driving dynamics
Wheel location is the same for all three suspension variants: a 3-link suspension locates the wheels at the front, while at the rear this is done by a multi-link independent suspension which has already impressively demonstrated its unrivalled wheel location qualities in the preceding model. In the new SLK this has forged aluminum hub carriers, in order to reduce unsprung masses even further for even better handling. All models in the new SLK-Class also have a torsion bar stabilizer, which is attached directly to the body.
The sports suspension has a stiffer damper setup, shorter suspension springs and torsion bar stabilizers with a larger cross-section. The suspension is also lowered by 0.39 inches. The roll control system has been reinforced to achieve even smaller roll angles when cornering at speed.
Suspension with automatic, continuously adjustable damping
The suspension with automatic, continuously adjustable damping, which is included in the optional Dynamic Handling package, sets new standards. It allows sporty and agile handling for maximum driving pleasure on winding country roads. An electronic system automatically and continuously ensures that the dampers are always set to suit the driving situation. The response time is normally only around 10 milliseconds.
Setting the basic characteristics of the suspension is still left to the driver, however, using a switch that enables him to choose comfortable or sporty damping characteristics. At the touch of a button he therefore has a suspension setup available which offers sport or comfort settings. If he chooses the sport setting, he is opting for a driving experience with a very high level of dynamic response.
Like the sports suspension, the suspension with variable damping is equipped with torsion bars with a larger cross-section, and the suspension is lowered by 0.39 inches.
Brakes for sporty driving enjoyment
The proven, dual-circuit hydraulic braking system and the distribution of the two circuits to the front and rear axles has been adopted from the preceding model. All variants are equipped with single-piston floating caliper brakes at all corners.
The brake covers at the front axle were optimized in the wind tunnel for even more efficient cooling of the brakes and wheel bearings, and to protect the brake discs from road debris.
Electric parking brake
The electrically operated parking brake in the new SLK helps in the design of a generous interior. Its switch is located in the dashboard, under the rotary light switch. Pressing it engages the electric parking brake, and pulling releases it. In models with an automatic transmission the brake is released automatically as soon as the engine is running, the transmission is in the D or R position, the driver has a fastened seat belt and the accelerator is pressed.
Direct and comfortable - the steering of the SLK
The 2012 SLK-Class features the hydraulically assisted Direct-Steer system which increases the agility and controllability of the SLK and improves steering comfort when parking as less effort is required. It combines these attributes with predictable and safe steering characteristics at high speeds. As a result, the agile roadster corners even more willingly and precisely, allows relaxed cruising on motorways and makes for even more exhilarating driving pleasure.
The new Direct-Steer system was developed from the familiar speed-sensitive steering that Mercedes-Benz offers for many of its models. With this system, the steering effort depends on the vehicle speed - the effort required increases with the speed. In practice, this means more steering comfort during parking maneuvers and more safety at higher speeds, for example on highways, where a greater steering effort ensures safe straight-line stability.
The new Direct-Steer system retains these positive attributes of speed-sensitive steering and adds a variable steering ratio that changes according to the steering angle. The ratio is indirect when the steering is centered, which ensures good straight-line stability and therefore a high level of safety. In contrast to other variable steering systems, the ratio of the Direct-Steer system increases rapidly after a steering angle of 5 degrees, becoming extremely direct from a steering angle of just 100 degrees. Only relatively small steering movements are then needed to make course corrections.
During city driving the driver needs to perform less pronounced steering movements, making quick changes in direction possible with less effort. The Direct-Steer system is even more impressive on winding country roads, where only small steering movements are sufficient to steer the vehicle. Even on tighter bends, the driver's hands hardly need to change their grip on the steering wheel. Rapid sequences of bends can be mastered almost intuitively, safely, precisely and enjoyably.
Despite its remarkable performance, the key component of the Direct-Steer system is simply a steering rack. Its secret lies in the teeth cut into it: in the middle these teeth are slightly wave-shaped, with varying side profiles. Further outward the teeth are spaced at varying distances apart so the change in steering ratio is produced by purely mechanical means. With this solution, Mercedes engineers have been able to dispense with the complex actuators and sensor systems used by other variable steering systems. The advantages include very low complexity and weight. The system always responds predictably and consistently while other variable steering systems sometimes require rapid adaptation by the driver in rapidly changing situations.
ECO steering servo pump lowers fuel consumption
Driving straight ahead in the new SLK also means saving fuel. This is ensured by an ECO steering servo pump as standard in all SLK models. Its centerpiece is an electrically actuated proportional solenoid valve which variably opens a bypass aperture at the pressure connection to feed the steering gear with just the right amount of fluid. As the steering has a lower energy requirement when driving straight ahead, the pressure in the steering system can be minimized and less energy is consumed.
Advanced safety technology
The 2012 Mercedes-Benz SLK sets new safety standards in the roadster segment. The safety experts have long adhered to the motto, "The best or nothing", coined by Gottlieb Daimler. Far from being satisfied with achieving rating targets, they work intensively on attaining a level of safety which far exceeds the standards required by the world's legislators. The most important measure of their work is not the laboratory or crash test facility, but actual, real-life accidents. They call the results of their work Real Life Safety, a concept which is based on research into thousands of accidents. Using this irrefutable evidence, the Mercedes-Benz engineers have developed or initiated most of the assistance systems which today effectively support drivers and have been adopted by many of the company's competitors.
ATTENTION ASSIST and ADAPTIVE BRAKE as standard
The new SLK also features a unique combination of driver assistance systems which help to avoid accidents, including the drowsiness detection system ATTENTION ASSIST. Thanks to this system, the roadster develops a precise feeling for the level of attentiveness of the driver and can provide an early warning of overtiredness.
Other standard equipment includes the ADAPTIVE BRAKE which consists of ABS, the acceleration skid control system ASR and also active yaw control (GMR). In addition, it features the following functions:
- supports the driver when accelerating uphill from a standstill, by preventing the vehicle from unintentionally rolling backwards;
- keeps the vehicle stationary without having to keep the brakes applied continuously - for example when waiting at traffic lights (HOLD function);
- as soon as the driver abruptly steps off the accelerator, it brings the brake pads into light contact with the brake discs as a precautionary measure, so that the necessary braking pressure can be attained quicker in the event of emergency braking;
- in wet conditions it applies light brake contact, without the driver even noticing, to dry the brake discs.
Safety and comfort
Those wishing to do so can extend the range of assistance systems in the new SLK even further with the addition of features enhancing both safety and comfort:
The Lighting Package provides additional lighting functions (active curve illumination and cornering light function), which are activated depending on the driving conditions
The optional PARKTRONIC with Parking Guidance supports the driver when parking. Its ultrasonic sensors measure the length of parking spaces as the car drives past; the cockpit display then provides a schematic representation of the recommended parking maneuver.
Taking into account all of the requirements of the rating institutes
In developing the new SLK, the requirements of Euro NCAP as well as all of the global consumer ratings have been taken into account. This has contributed to the development of the bodyshell structure of the vehicle, which follows established concepts and has been optimized in a number of detailed areas. These include, among other things, reinforced members, a new side impact structure and new fiber-reinforced roll-over bar.
In the event of an accident, up-front sensors and lateral satellite and roll-over sensors help the central control unit to predict the nature and severity of the accident. New, additional pressure sensors in the doors as well as acceleration sensors in the front bumper help in detecting an impact with a pedestrian.
New headbag and crash-responsive head restraints
The restraint systems with two-stage driver and front passenger airbags have also been enhanced. A new feature is the headbag, which provides generous lateral protection for the head impact area. An additional thorax airbag in the seat backrest protects the upper body in the event of a side impact. Both the driver and passenger are provided knee airbags as well. The seat belts, with belt buckle tensioners and speed-sensitive belt force limiters, serve to highlight the high safety standards of Mercedes-Benz.
Another new feature finding its way into the standard equipment of the 2012 SLK comes in the form of the NECK-PRO crash-responsive head restraints, developed by Mercedes-Benz. They support the driver's and passenger's heads in the event of a rear impact and reduce the risk of whiplash.
An intuitive companion
A radio and other entertainment media are a given in today's vehicles, electronic navigation systems are almost as common, and customers demand to integrate a mobile phone easily into the onboard network. To meet these requirements in the best possible way, Mercedes-Benz has equipped the new SLK with latest-generation telematics.
The sophistication of the head unit is immediately apparent from the large color display. This monitor is positioned in the upper section of the center console, so that the driver is able to see the information provided without taking his eyes fully off the road. It can also be easily viewed by the passenger.
The head units share a common interface known as the "central controller". In the interests of relaxed and ergonomical operation, it is located within easy reach in front of the center armrest. This extremely sophisticated, metal rotary/pressure control can be moved in eight directions, and can also activate or confirm additional functions by rotating or pressing it. Navigating through the main menus and sub-menus is effortless and thanks to new user-friendly logic the system is quickly and intuitively mastered.
The head units are connected to eight loudspeakers and feature speed-sensitive volume control from 12 mph, which increases the radio volume with the vehicle speed. All the units are also protected against theft by electronic assignment to the specific vehicle.
Audio 20
The basic Audio 20 radio is combined with a large TFT color display with a screen diagonal of 5.8 inches and a resolution of 400 x 240 pixels as a head unit. Audio 20 features:
integrated AM/FM tuner,
audio amplifier with 4x25 watts
MP3-capable CD player and AUX connection in the glove compartment
Bluetooth interface for hands-free calling
Bluetooth audio streaming
COMAND System
Optionally available is the COMAND head unit featuring the voice-operated Voice Control system. The display screen for this unit is a high-resolution TFT color display with a 7-inch screen capable of representing 800 x 480 pixels.
10 GB of storage for compressed audio files (mp3, wma and aac formats) is now included. COMAND also includes a 6-disc CD/DVD changer.
The Music Search function enables drivers and passengers to search the hard disc, SD memory cards, USB sticks, CDs and DVDs for specific music tracks and artists. The search can be according to various criteria, for instance album, music category or composer.
The fast hard-disc navigation system of COMAND also has new features such as 3D city views and recording of drive routes which can be recalled later. The driver can also set specific personal destinations via an SD card and four alternative routes can be displayed on the navigation map, one of them an economical variation. COMAND also includes a voice-operated control system for audio, telephone and navigation with convenient whole-word recognition.
Sound system - striking the right note
Audiophiles are able to choose the optional Premium 1 Package featuring Harman/Kardon® surround sound system. This features an additional MOST amplifier with DSP and an output of 8 x 50 watts plus ten high-quality, high-performance loudspeakers. All the amplifier channels of the sound system are equipped with frequency compensation individually suited to the vehicle acoustics. Bass, treble, volume, balance and fader can be individually adjusted.
Telephony - reachable at any time
Both the Audio 20 radio and the COMAND system have an integrated Bluetooth hands-free system for mobile phones. The hands-free system can be operated via the multifunction steering wheel or the keys on the head unit. Bluetooth can also be used to transfer contact data from a mobile phone to the head unit.
