2012 Mercedes-Benz SLK Coupe/Roadster - Comprehensive Technical Guide
INTRODUCTION
The 2012 Mercedes-Benz SLK represents the third generation of a sports car that rocked the automotive world when it unveiled the first automatic retractable hardtop in its segment. The original SLK re-energized the small roadster market segment, which expanded to include such competitors as the Porsche Boxster and the BMW Z3.
The First Retractable Hardtop in Modern Times
Spearheading a trend that's still changing the auto industry, the latest SLK is best known for its distinctive retractable hardtop. With the top up, it's a quiet, weather-tight coupe - push a button, and 20 seconds later, the car is topless.
Thanks to its pivoting rear window, the folded roof of the SLK takes up relatively little trunk space. Like the retractable hardtop of the larger SL model, the rear window of the SLK pivots to match the curvature of the top as it's being lowered. The folded top provides more trunk room than ever - enough for a long weekend trip for two.
MAGIC SKY CONTROL
SLK customers can order an optional Panorama Roof that features a tinted see-through polycarbonate panel or - making it's debut - the optional MAGIC SKY CONTROL, in which the tinting of a translucent glass panel can be controlled by the driver or passenger. Using electrochromic technology similar to automatic dimming mirrors, a button on the overhead console can instantly change the roof panel from transparent to heavily tinted.
Direct Injection V6 Engine
The SLK350 is powered by a new 3.5-liter V6 engine that features direct injection and multispark ignition. With even more power and better fuel economy than its predecessor, the new SLK engine generates 302 horsepower and 273 lb.-ft. of torque.
Its brand-new engine block also features 60-degree cylinder angles, so that an internal balance shaft is no longer needed. With cast-in Silitec cylinders, the cylinder block, heads and pistons are aluminum, while the crankshaft, connecting roads and valves are made of special forged steel.
ATTENTION ASSIST
Making its debut on the new SLK line is "ATTENTION ASSIST" as standard equipment. This innovative safety feature couples a steering movement sensor with intelligent software that can identify the erratic steering corrections drivers make as they begin to get drowsy. When the standard-equipment system senses drowsiness, a warning message appears in the instrument cluster, and the driver is also alerted by a display that says, "Time for a rest!"
The software receives signals from the steering sensor and monitors 70 different parameters that have proven to be strong indicators of fatigue and drowsiness. Years of research and testing have shown that drowsy drivers make minor steering errors that are corrected in identifiable ways. Sophisticated enough to disregard sporty driving involving high cornering speeds and lane changes, the system works between 50 and 100 mph. Elegant in its simplicity, ATTENTION ASSIST essentially adds new intelligence to existing sensors.
Hardbody with a Hardtop
The unitized body of the latest SLK uses generous amounts of high-strength steel alloy, which makes the body very strong without substantial increases in weight. The entire body shell is zinc-coated for long-term corrosion protection, and the SLK makes use of clear-coat paint with enhanced scratch resistance that was initially developed in the nanotechnology sector.
BACKGROUND
A bold concept for a small topless roadster - the Mercedes-Benz SLK - was unveiled at the Turin Auto Show in 1994, followed by the debut of a second SLK concept car featuring a trendsetting retractable hardtop in 1995 at the Paris Show. In 1996, the production SLK coupe/roadster was launched in Europe.
North American Car of the Year Winner
When the SLK coupe/roadster first arrived in the U.S. market in January 1997, the new roadster was greeted by an impressive number of automotive awards, including the prestigious 1998 North American Car of the Year, which is determined by an independent jury of the top 50 automotive journalists in the U.S. and Canada.
The SLK was initially launched in the U.S. with a 185-horsepower supercharged four-cylinder engine and a five-speed automatic transmission. However, as the car evolved, a V6 engine and a sportier six-speed manual transmission were added, along with an eye-catching Sport package and ultimately an AMG version powered by a 349-horsepower supercharged V6.
A Second-Generation Winner
Sportier, stronger and more appealing than ever, a second-generation SLK arrived for the 2005 model year, also marking the debut of the Mercedes-Benz twin-cam V6 engine family. Slightly larger than its predecessor, the exterior design of the new SLK featured dramatic cues from the world of Formula 1 racing - an arrow-shaped nose, long front hood, steeply sloped windshield and a tapered, wedge-shaped silhouette.
In 2009, the SLK enjoyed a significant facelift, which included exterior design with an even stronger influence from Formula I race cars, as well as new chronometer-type gauges inside and a new direct-steer system with variable-ratio rack gearing. This version served the SLK line well up to the launch of the third-generation car.
EXTERIOR
Futuristic Design with a Retro Touch
The third-generation SLK boasts a wide, upright front grille with a long front hood as well as relatively long doors and a short rear section. The new car has a futuristic look, and at the same time, the design of its nose is reminiscent of the classic 190SL of the 1950s - considered by many to be "the original SLK."
Short front and rear overhangs focus the eye on its wheels, and flared fenders form a dynamic body line suggesting motion and speed. When the roof is closed, swept-back Apillars continue the lines of the front hood and transfer them to the rear. In the center of its broad grille, a large Mercedes-Benz star is bracketed by a single contoured lamella that accentuates the car's bold stance. Standard halogen headlights feature LED daytime running lights integrated in the front bumper.
Optional Bi-Xenon Headlights
With a distinctive twin-tube design, optional bi-xenon headlights produce light that more closely resembles natural daylight, which provides better night visibility as a result. The bixenon lights come with active curve illumination, which automatically angles the main beam tube up to 20 degrees whenever the steering wheel is turned. In the other tube, cornering lights also come on whenever the turn signals are on.
The bi-xenon light package includes a headlight cleaning system that uses water pressure to extend telescopic arms from the bumper. On the end of each arm, two nozzles spray highpressure cleaner onto the headlights, and springs retract the arms back into the bumper.
LED Taillights
The 2012 SLK uses rows of LEDs for the rear running lights, turn signals and brake lights. A third LED brake light is flush-mounted in the trunk lid above the Mercedes-Benz star insignia.
Slipperier Aerodynamics
The 2012 SLK's coefficient of aerodynamic drag (Cd) is impressive for a convertible - 0.30. Although frontal area has increased slightly, its total aerodynamic drag is still lower than the previous car.
While low drag numbers translate directly to better fuel economy, careful work in the wind tunnel also makes for a quieter car. With the retractable hardtop closed, noise levels inside the new SLK are as low as a fixed-roof coupe. Examples of wind tunnel results include air spoilers at the front and rear wheels, full underbody paneling, streamlined outside mirror housings and an air flow "break-away" lip at the back edge of the trunk lid.
Keeping Its Feet on the Ground
One of the goals in aerodynamics is to minimize lift and, as a result, improving directional stability at high speeds. The design of the SLK's underbody panels, wheel spoilers and even the lip on the trunk lid help reduce the forces that can otherwise begin to lift a car off the ground at high speeds, like an airplane wing.
Drive Under the Breeze with a Wind Deflector
Even after careful development work in the wind tunnel, Mercedes engineers know pockets of air turbulence still form behind the occupants when the top is down. They discovered that this distracting air buffeting can be prevented by using a removable wind deflector. On the SLK, a fabric deflector mounts to the roll bars, helping to distribute air more evenly and smoothes out its flow. An optional AIRGUIDE wind deflector mounts to the back of the roll bars. Consisting of two Plexiglas panels, the wind deflectors can be adjusted independently by the driver and front passenger.
THE ROOF
Folding Hardtop Sensation
When the SLK made its debut in 1996, the car's automatic retractable hardtop caused a sensation and started a new trend in convertibles. The folding hardtop in the latest SLK opens and closes even faster, and its space-saving design creates more trunk room when the top is down.
Coupe to Roadster in 20 Seconds
The new SLK transforms itself from a quiet, weather-tight coupe to a topless roadster (or back) in 20 seconds - two seconds faster than its predecessor and a full five seconds faster than the original car. When the roof goes down, the rear window swivels to match the roof curvature, so it takes up little room in the top of the trunk.
Six Hydraulic Cylinders Make It All Work
Six hydraulic cylinders operate the top - two control the roof, while another pair lock the roof to the windshield frame, and two more power the tubular frame. A new four-link hinge opens the roof more easily than the previous seven-link setup, and a multi-piston hydraulic pump housed in the cross member behind the seats operates the six servos. An electromagnetic valve integrated in the pump controls its operation, and limit switches monitor every step of the sequence. A display in the center of the dash indicates when the roof is fully open or closed.
MAGIC SKY CONTROL
While the standard roof panel is made of body-color polycarbonate plastic, an optional Panorama Roof features a tinted see-through panel. The roof is also available with MAGIC SKY CONTROL, in which the tinting of the transparent glass panel can be controlled by the driver or passenger. In an instant, a button on the overhead console can change the roof panel from transparent to heavily tinted.
This roof uses electrochromic technology similar to automatic dimming mirrors, but can be controlled by the occupants. Sandwiched between two layers of glass, a chemical film called a matrix polymer holds oblong nano particles that line up uniformly when electrical current is applied, allowing light to pass through. When the electrical current is turned off (via a button above the rearview mirror), the nano particles disperse randomly, reducing light and tinting the roof panel.
MAGIC SKY CONTROL was tested extensively before production, including in Death Valley, one of the world's hottest places with temperatures exceeding 120 degrees Fahrenheit. Measurements using a star pyranometer show that with MAGIC SKY CONTROL at its dark setting, the intensity of the sun's rays is only 1/20th of the original level.
To view the complete technical guide, please download the Comprehensive_TechGuide_2012_SLK.pdf file.
