More powerful, more economical, more intense: rediscovering intelligent roadster driving enjoyment
The Mercedes-Benz SLK-Class Roadsters have long captured the hearts of sports car enthusiasts. Incorporating around 650 newly developed components, the SLK models of 2008 are even more dynamic and now offer an even more emotionally charged driving experience.
Since their first appearance in 1996, the compact SLK Roadsters have come to symbolize the dynamic Mercedes-Benz brand image. Already a familiar sight on our roads, the second-generation two-seater is to be further enhanced with the implementation of extensive measures in 2008, the aim being to further emphasise the car's sporty character and continue the SLK-Class success story by introducing new, dynamic, powerful elements. Some 310,000 first-generation roadster models were sold between 1996 and 2004. And approximately 185,000 customers – some 60,000 of them in Germany alone – have already purchased the second-generation model since its launch in March 2004 (figures at year-end 2007). This means that total unit sales of the SLK Roadster are now approaching the half-million mark.
The new-generation SLK displays new sporty highlights, further enhancing the appeal of the successful two-seater with the trendsetting vario-roof that transforms the car from a roadster into a weatherproof coupé in a matter of seconds.
Distinctive character: even more pronounced arrow shape at the front end and a diffuser-style rear end
The designers have given the already dynamic-looking two-seater an even sportier appearance. Eye-catching features include the new-look front bumper with a modified air-dam arrangement and a more pronounced arrow shape. The area around the Mercedes star is also further emphasized. In addition, the designers have modified the rear end by introducing a diffuser-style lower section that makes the Roadster appear more powerful when viewed from behind – an effect that is enhanced considerably by the trapezoidal exhaust tailpipes and the AMG-inspired darkened tail lights. The larger exterior mirrors feature LED indicators with a pronounced arrow shape, while the range of light-alloy wheels has been enhanced with new designs.
High-quality cockpit and new three-spoke sports steering wheel
Many of the interior details have also been redesigned and upgraded following a careful process of material selection. Particular attention was given to optimizing the interior so as to make it even more driver-oriented. Highlights include a new three-spoke sports steering wheel with multifunction buttons and a new instrument cluster with redesigned bezels.
New "gullwing red" leather appointments will be available – reminiscent of the interior appointments in the legendary 300 SL gullwing model. Further new additions include nappa leather appointments in "natural beige", which perfectly complement the new "light burl walnut" wood trim.
Enhanced audio and telematics systems
Mercedes-Benz is installing the new NTG 2.5 audio and telematics generation in the SLK for the first time. It is easier to operate and offers an even wider range of useful functions. Integrated into every radio is a hands-free system with Bluetooth technology. As an option, a new media interface in the glove compartment allows the full integration of mobile audio devices such as an iPod, which can then be operated via the audio system's user interface.
Together with the new telematics generation, Mercedes-Benz is also offering the easy-to-use, enhanced LINGUATRONIC voice-operated control system as an optional extra in the SLK-Class for the first time.
Voluminous surround sound even when the roof is open
Passengers can enjoy a unique listening experience, regardless of whether the vario-roof is open or closed, thanks to the optionally available harman kardon® Logic7® sound system. Rich and voluminous surround sound makes for crystal-clear listening pleasure.
High-revving sports engine: higher output and much lower fuel consumption
The sporty credentials of the 2008 SLK generation are further enhanced by modified powerplants that consume less fuel and, therefore, emit less CO2. The six-cylinder sports engine in the SLK 350 offers substantially more power and torque. Only the SLK 55 AMG retains its familiar engine – an eight-cylinder unit that has lost none of its mesmerising performance capability and remains a unique selling point in the SLK segment.
The Mercedes-Benz engineers paid special attention to the high-revving V6 engine that makes its debut in the SLK 350. They sought much more than minor enhancements, substantially enhancing the six-cylinder unit by making sweeping changes to the mechanical setup. Three characteristics add a new dimension in driving enjoyment:
• Flexibility through high engine speeds
• Substantial increase in output
• A sporty sound that fires the emotions.
Up to 7200 revs per minute
The 3.5-liter engine effortlessly achieves engine speeds normally well out of bounds for series-production engines of this displacement. Its rated output is reached at 6500 rpm - maximum engine speed peaks at 7200 rpm. This outstanding high-revving flexibility turns the six-cylinder unit into a thoroughbred sports engine.
Its sporty pedigree is clearly noticeable behind the wheel. The engine is always responsive, more powerful than its predecessor and instantly reacts to movements of the accelerator pedal - conjuring up a touch of race track atmosphere in the cockpit. Still, comfortable driving characteristics are fully retained whatever the operating conditions.
Output increased by 32 hp
An increase in output, courtesy of the engine enhancements, adds to the decidedly sporty feel. Although the displacement remains the same at 3498 cc, the V6 now develops 300 hp – some 32 hp more than its predecessor. Peak torque has also been boosted by 7 lb-ft to 265 lb-ft at 4900 rpm. From as low as 2,000 rpm it develops 258 lb-ft, delivering impressive pulling power and outstanding performance. The SLK 350 accelerates from zero to 60 in 5.3 seconds.
The sports engine in the SLK 350 is based on the existing V6 unit but features a range of modified components. Key modifications include:
• Enhanced, weight-optimized pistons with a curved surface and a higher compression ratio of 1:11.7 (previously 1:10.7) ensure optimized efficiency.
• Single-stage intake manifold (no internal flaps) ensures a high charge even at high engine speeds.
• To address the fundamental limitations of the single-stage intake manifold at engine speeds below 4000 rpm, the camshaft position has been advanced by 5 degrees of crank-angle both on the intake and exhaust sides. The high revving quality has thus been retained both at idle speed and under partial load.
• Lightweight valves made out of ultra-high-strength and high-temperature-resistant steel. The sodium-cooled valve stems for the exhaust valves have a 3.4-mm bore.
• Conical springs with heavily dampened natural vibration characteristics reliably close the valves even at high engine speeds.
• A tri-oval chain sprocket, whose triangular form is barely noticeable, effectively counteracts chain-drive vibration that tends to increase at engine speeds above 6,300 rpm. The chain sprocket generates inversely phased amplitudes, thus reducing chain vibration and, in turn, the forces acting on the chain.
• A red accent atop the engine cover provides a visual distinction
Emotive sound design underlines high-performance credentials
Further aspects which add to the emotional appeal of the new engine include modified sports-engine acoustics for a more aggressive sound. In combination with the 7G‑TRONIC automatic transmission, the engine management system blips the throttle automatically during downshifts. Aside from producing an extremely sporty sound, this throttle-blipping function reduces load alteration effects.
Other engines to choose from
The engine line-up for the second generation of the successful SLK-Class is being enhanced for the facelift:
• The SLK 300 has been further improved with respect to fuel economy and, therefore, CO2 emissions. It continues to produce 228 hp from its 2,996 cc displacement, delivering 221 lb-ft of torque between 2500 and 5000 rpm. 0 to 60 takes 6.1 seconds.
• The SLK 55 AMG is equipped with the familiar 5.5-liter V8 powerplant developing 355 hp and a peak torque of 376 lb-ft. 0 to 60 mph takes 4.9 seconds before a top speed of 155 mph (electronically limited) is reached.
Sporty six-speed manual transmission or seven-speed automatic transmission
Standard equipment for the SLK 300 includes a six-speed manual transmission, which provides fast, sporty gear changes coupled with supreme ease of shifting. The 7G‑TRONIC automatic transmission with seven speeds is optional on the SLK 300 and standard equipment on the SLK 350. The optional 7G‑TRONIC Sport automatic transmission, with shift paddles on the steering wheel and shorter shift times, delivers even more performance in these two models. The AMG Speedshift 7G-TRONIC, which has been specifically tuned by AMG, comes with aluminium shift paddles on the steering wheel in the SLK 55 AMG.
New direct-steer system for outstanding agility and tangible driving pleasure
A newly developed direct-steer system with variable steering assistance further highlights the qualities of the sporty chassis. The system provide agility and maneuverability when driving on twisting rural roads, steering comfort when parking and assured steering characteristics when traveling at high speed.
The direct-steer system is based on the previously available speed-sensitive power steering system and operates by purely mechanical means - there is no need for elaborate actuators and complex sensors, which would otherwise impair the direct flow of forces between the wheels and hands, compromising steering precision. At its heart is a new rack with innovative gearing, which ensures that the steering ratio changes in tune with the steering angle. The ratio is indirect when the steering is in a central position to ensure excellent straight-line stability and, therefore, a high degree of assuredness when traveling at high speed. At a steering angle of just 5 degrees, the ratio starts to increase rapidly and the steering becomes much more direct. As a result, the number of steering wheel revolutions from lock to lock is reduced by approximately 25 percent. This means that, even in city traffic, relatively little steering input is required to correct the car's path. The effect of the direct-steer system is all the more impressive in bends on rural roads. Small steering movements are all that is needed to pilot the vehicle, virtually eliminating the need to reposition the hands on the steering wheel; fast sequences of bends on rural roads can be negotiated almost intuitively – with assurance, precision and a healthy dose of driving enjoyment. All of which translates into far more agile handling.
SLK 55 AMG with direct-steer system and even more striking appearance
The SLK 55 AMG is now even more dynamic. The appearance of the sporty roadster now reinforces the car’s special status. The redesigned front apron with a more pronounced arrow-shape, the modified Mercedes star, enlarged air dams and a black-painted transverse fin on the lower section ensure a distinctly masculine appearance. Large, round foglamps with chrome surrounds are now positioned further outwards, enhancing the impression of width. The heat from the integral engine oil cooler is vented via side outlets in the front apron. The specific SLK 55 AMG bodystyling also includes AMG side skirts, the muscular AMG rear apron with a black insert and the AMG trunk lid spoiler.
New features also include the projection-beam headlamps with dark surrounds and the redesigned exterior mirrors. The mirrors are now larger to provide better rearward visibility while LED indicator repeaters in an arrow design also ensure increased safety. New, high-sheen 18-inch AMG light-alloy wheels in a double-spoke design provide a striking appearance when viewed from the side. With a width of 7.5 and 8.5 inches respectively, the AMG light-alloy wheels are fitted with size 225/40 (front) and 245/35 (rear) tires. Outstanding deceleration values are ensured by the AMG high-performance braking system with internally ventilated and perforated brake discs, size 345x30 mm, at the front. The newly developed direct-steer system is also part of the standard specification.
Functional interior with new AMG instrument cluster
In the functional and sporty interior of the SLK 55 AMG, the new AMG ergonomic sports steering wheel with its three-spoke design gives a visual hint of the direct steering feature. The grip area is specially shaped and lined with perforated leather, while the vertical spoke is embellished by a silver-coloured insert. Two aluminium AMG shift paddles allow manual gear selection.
The AMG instrument cluster with a 200 mph speedometer scale, silver/red needles and AMG lettering also has a new look; the new graphics ensure that vehicle speed and rpm are even more easily legible.