Mercedes SLK Facelift: In Depth

WCF readers have already seen the facelifted Mercedes-Benz SLK-Class in many pictures and articles we have published, but since such a car deserves to be known in depth, here is another chance for you people to do so, with the complete press release and more images of this beautiful new roadster.

Mercedes-Benz has lately treated any change in its cars as if they were “new generations” and the facelifted Mercedes-Benz SL-Class is a proof of that, just like the E-Class, back in 2006. Fact is a new generation car only comes with significant platform changes, and none of these cars has gone through any modification of this sort. Fortunately, the 2008 SLK has been treated by Mercedes-Benz as what it really is, a facelifted model.

This is no shame for the car, since it managed to get even better than the previous SLK. Among its improvements is the direct-steer system, an equipment Mercedes-Benz is really betting on, since all recent presentations, from the CLC-Class to the SL-Class, are offering it. Clearly trying to beat BMW in dynamics, the Sttutgart automaker gave its vehicles a variable steering ratio, what improves turning speed in corners and makes city parking maneuvers easier.

But there’s plenty more, such as a new high-revving 3.5-litre V6 (it reaches up to 7,200 rpm) delivering 305 hp, for the SLK 350, improved output for the SLK 200 Kompressor (184 hp) and general reduction in fuel consumption.

More than telling you about all the improvements the car has received (besides the visible ones), we invite you to read Mercedes-Benz information on this fantastic car. And to check out all the pictures, as it will take a while for the car to be seen on the streets.

Press Release

Rediscovering roadster driving pleasure

The key facelift measures at a glance

Technology

SLK 350 with a high-revving V6 sports engine with a displacement of 3498 cc and an output of 224 kW/305 hp at 6500 rpm (+24 kW/33 hp). Fuel consumption 9.5 litres per 100 km (-1.1 litres), CO2 emissions 219 g/km (-23 g/km). Sporty, emotion-charged soundtrack.

SLK 200 KOMPRESSOR with a four-cylinder inline engine with a displacement of 1796 cc and an output of 135 kW/184 hp at 5500 rpm (+15 kW/21 hp) . Fuel consumption 7.7 litres per 100 km (-1.0 litre), CO2 emissions 182 g/km ( 27 g/km).

SLK 280 with a reduction in fuel consumption of 0.4 l/100 km, CO2 emissions 11 g/km.
Optional direct-steering system combines agility and manoeuvrability with steering comfort when parking and assured steering characteristics when travelling at high speeds.

Design

Front bumper with new design and more pronounced V-shape.

Area around the Mercedes star stands out more boldly, the all-round chamfered edge is more striking.

Front fog lights with chrome surrounds.

New-look rear bumper to give the tail a more powerful aspect, diffuser-look styling.

Exhaust tailpipe in new, angular design (trapezoidal).

Darkened tail lights (like SLK 55 AMG).

Exterior mirrors with larger mirror surface and arrow-shaped LED indicators.

New short aerial, suitable for automatic car washes.

New 3-spoke sports steering wheel with multifunction buttons.

New instrument cluster with red needles, dial bezels in 3D look, plus chrome surrounds for the tubes and the clock/fuel gauge.

Upgraded trim elements/switches/pushbuttons in new colours.

Chrome insert below headunit.

New appointments colours: "gullwing red" and "natural beige".

New wood colours: "pale burr walnut" and "black ash grain".

Shift and selector levers with new leather-and-chrome trim.

Sporty looking trim strip on passenger side.

Modified power window switches.

New "palladium silver metallic" paint finish, plus the exclusive SLK finish "prehnite green metallic".

Equipment

New telematics generation (NTG 2.5) with additional functions and improved user friendliness.

Available with a choice of Audio 20 CD, Audio 50 APS with DVD navigation system or COMAND
APS with high-resolution 6.5" colour display, hard-drive navigation, 4GB MUSIC REGISTER for storing compressed audio files, plus SD memory card slot.

Option of new and enhanced Harman Kardon® Logic7® sound system with Dolby 5.1/DTS and an output of 500W (previously 380W).

All headunits feature Bluetooth hands-free facility as standard.

Media interface as an option - universal interface in glove compartment for portable audio devices (e.g. iPod).

Optimised LINGUATRONIC voice-operated control system (available for the SLK for the first time).

In Short

The Mercedes-Benz SLK-Class Roadsters have long captured the hearts of sports car enthusiasts. Following an extensive facelift 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. Key visual enhancements include new-look front and rear sections, as well as a meticulously modified interior with a new instrument cluster and three-spoke sports steering wheel. The high-revving V6 sports engine in the SLK 350 developing 224 kW/305 hp and an optionally available direct-steer system truly bring the bold, dynamic character of the two-seater to the fore. Furthermore, all of the engines in the line-up are now far more economical on fuel and therefore emit even less CO2, despite a substantial increase in output in some cases. The new-generation SLK models will be available for delivery from April 2008.

Since their first appearance in 1996, the compact SLK Roadsters have come to symbolise Mercedes-Benz' dynamic brand image. Already a familiar sight on our roads, the second-generation two-seater is to be further enhanced with the implementation of a raft of 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 and powerful elements. Some 310,000 first-generation roadster models were sold between 1996 and 2004. And around 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 second-generation SLK has therefore retained the car's quite unique status in this market segment.

The new-generation SLK blazes a trail of new sporty highlights, bestowing yet greater appeal on this thriving 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 V-shape at the front and a diffuser-style rear

The designers have honed the looks of the cult two-seater for added sportiness. Eye-catching features include the new-look front bumper with a modified air-dam arrangement and a more pronounced V-shape, while the area around the Mercedes star now stands out more boldly. The designers have also remodelled the vehicle's tail, with the diffuser-look styling at the bottom giving the Roadster an even more powerful appearance from the rear too. This is further emphasised by the trapezoidal exhaust tailpipes and the AMG-inspired darkened tail lights. The now larger exterior mirrors feature LED indicators with a pronounced arrow shape, while the range of light-alloy wheels is also almost entirely new.

High-quality cockpit and new three-spoke sports steering wheel

Many of the interior's details have undergone remodelling too, and the interior has been refined as a whole by meticulous material selection. Particular care was taken to optimise the interior in such a way as to make it that much more driver-focused again. Centrepieces include a new three-spoke sports steering wheel with multifunction buttons as well as a new instrument cluster with intriguing-looking dial bezels.

New "gullwing red" leather appointments will now be available, which are reminiscent of the interior appointments in the legendary 300 SL gullwing model. Further new additions include nappa leather appointments in "natural beige", which complement the new "pale burr walnut" and "black ash grain" wood trims perfectly.

Enhanced audio and telematics systems

Mercedes-Benz is installing the new NTG 2.5 generation of audio and telematics componentry in the SLK for the first time. This boasts improved user friendliness together with even more handy functions. Standard features integrated in every radio include a hands-free facility using Bluetooth technology, plus - as an option - a new media interface in the glove compartment, which enables mobile audio devices such as the iPod to be fully integrated into the audio system and operated from its control panel.

The switch to the new telematics generation now sees Mercedes-Benz offering the optimised LINGUATRONIC voice control system, renowned for its outstanding operation, as an option for the SLK-Class for the first time.

Voluminous surround sound even with the roof down


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, the like of which has never before been associated with a roadster.

High-revving sports engine: added power and considerably lower consumption

Making a mighty contribution to the sporty billing of the 2008 generation of the SLK are three reengineered drive units, which all make their mark with lower fuel consumption, resulting in reduced CO2 emissions. Both the four-cylinder engine in the SLK 200 KOMPRESSOR and the six-cylinder sports engine in the SLK 350 benefit from a substantial increase in output 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 devoted particular attention to the V6 sports engine with high-revving concept, which is making its debut in the new-generation SLK. By performing a major overhaul of the engine's mechanics, the engineers succeeded in giving the V6 unit a completely new lease of life. Although the displacement remains the same at 3498 cc, the engine now musters up 224 kW/305 hp at 6500 rpm - some 24 kW (33 hp) more than its predecessor. Torque has been upped too (+ 10 Nm) and now peaks at 360 Nm at 4900 rpm.

This has been achieved by raising the rev speed limit to 7200 rpm, at the same time as increasing the compression ratio, fitting a new intake manifold and making extensive modifications to the valve gear.

The new engine also strikes a far more emotive-sounding note after being deliberately tuned to deliver resonant sports engine acoustics, with overrun mode producing a particularly emotion-stirring sound. When partnered by the 7G TRONIC automatic transmission, the engine management furthermore triggers an automatic double-declutching function during downshifts - not only does this create a very sporty soundtrack, it helps to limit load-alteration effects too.

Yet despite its higher power output and such high-calibre performance, fuel consumption in the SLK 350 has been cut by a sizeable margin. With the six-speed manual transmission on board, combined fuel consumption is just 9.5 litres per 100 km, a remarkable reduction of 1.1 litres per 100 km; if the 7G-TRONIC automatic transmission is fitted, the sports engine limits itself to a mere 9.2 litres for every 100 km on the combined cycle - 0.9 litres less than previously. The cut in fuel consumption also lowers CO2 emissions by 23 g/km to 219 g/km on the automatic model (manual transmission: 227 g/km, a reduction of 28 g/km).

Choice of three further engines

Following the facelift, the engine line-up for the second generation of the successful SLK-Class will comprise three further variants:

The output of the four-cylinder supercharged engine has been boosted by 15 kW/21 hp (to 135 kW/184 hp), with torque increasing from 240 to 250 Newton metres. Combined fuel consumption has dropped by 1.0 litre to 7.7 l/100 km. This in turn reduces CO2 emissions by 27 g /km to 182 g/km.

The SLK 280 has likewise been optimised for lower fuel consumption, and therefore CO2 emissions. Fuel consumption has dropped by 0.4 litres to 9.3 l/100 km (automatic: -0.2 l to 9.1 l/100 km) and CO2 emissions by 11 g to 220 g/km (automatic: -6 g to 216 g/km)

At work under the bonnet of the SLK 55 AMG is the familiar 5.5-litre V8 powerplant delivering 265 kW/360 hp and 510 Nm of torque.

The three new models in the SLK range all come with a precision six-speed manual gearshift. The SLK 55 AMG retains the 7G-TRONIC Sport seven-speed automatic transmission. The optional extras available include a five-speed automatic transmission for the SLK 200 as well as the 7G-TRONIC seven-speed automatic transmission or, alternatively, the 7G-TRONIC Sport with shift paddles on the steering wheel for the six-cylinder SLK 280 and SLK 350 sports engine models.

New direct-steer system for outstanding agility and tangible fun at the wheel

A newly developed direct-steer system with variable power assistance that elicits the very best from the suspension's sporty capabilities is optionally available (standard on the SLK AMG 55). It combines agility and manoeuvrability on twisting country roads with light steering forces when parking and sure steering characteristics at high speeds.

The direct-steer system is derived from the previous speed-sensitive power steering and operates purely mechanically. This dispenses with the need for elaborate actuator units and complex sensors, which would otherwise impair the flow of forces between the wheels and hands, thereby compromising steering precision. At the heart of the system is a new rack with ingeniously devised gearing, which ensures that the steering gear ratio changes in tune with the steering angle. In and around the central position, the steering has an indirect ratio for good straight-line stability, resulting in tremendous assuredness when travelling at high speeds. At a steering angle of just 5 degrees, the ratio starts to increase very rapidly and the steering feels much more direct. As a result, the number of steering wheel turns from lock to lock is reduced by around 25 per cent with the new direct-steer system. Consequently, relatively small turns of the steering wheel are sufficient for changing course when driving in city traffic. Fast sequences of bends on rural roads, on the other hand, can be negotiated almost intuitively with relatively small steering movements - with assurance, precision and a healthy dose of driving pleasure.

Visually enhanced SLK 55 AMG

On a technical level, the SLK 55 AMG remains almost unchanged. The only differences are a few visual enhancements. The front end of the AMG model now features a new apron with a black-painted transverse fin and side air outlets, as well as darkened headlamps.

The trendsetting SLK

As trendsetters and technology leaders, the SLK-Class Roadsters have long enjoyed the image of a modern cult car. Even after the extensive modifications, the familiar outstanding qualities remain; for example, the vario-roof that transforms the Roadster into a coupé in 22 seconds, not to mention the comprehensive standard specification, including head/thorax sidebags, adaptive front airbags and two-stage belt-force limiters. Plus, the Roadster also comes with the option of the unique AIRSCARF neck-level heating system, which allows open-top driving pleasure all year round, even in the winter months.

Design and equipment

Open to extra sportiness: striking lines for an even sportier character

New front end with modified air-dam arrangement

Tail with powerful diffuser styling

New sports steering wheel and restyled instrument cluster

Cutting-edge technology for audio, navigation and telephone systems

State-of-the-art sound system for outstanding surround sound

The design mirrors the character: muscular shoulders, large wheels and a dynamic wedge shape with a long bonnet and short tail echo the intense power and sportiness of the SLK-Class Roadsters. This most masculine overall impression is complemented by a host of details with motor racing connotations that underline the great sports car tradition of Mercedes-Benz. These include a front-end design that takes its cue from the world of motor sport, wing-shaped sections in the radiator grille and a twin-pipe exhaust system.

During the course of the facelift programme, the designers have spiced up the visual appearance of the cult two-seater. Their styling enhancements for the new-generation SLK-Class were all about instilling yet more sportiness and an even greater sense of forwards surge.

Bolder front with more pronounced V-shape and new rear apron

The most eye-catching feature is the new-look front bumper with its modified air-dam arrangement. Instead of one large air dam in the centre and two smaller ones at the sides, large air dams on the left and right now dominate the picture. The vertical struts have been moved towards the middle where, together with the extra 14 millimetres of overhang, they emphasise the front end's more pronounced V-shape. The front fog lamps with their new, extra chrome surrounds are integrated into the three-dimensional ventilation grilles, which are likewise new.

The area around the Mercedes star is also moulded by sharper contours. An all-round chamfered edge that is positioned much higher than on the outgoing model gives the Roadster's face a more striking look, and combines with the more solid-looking horizontal louvres in the radiator grille to make the vehicle appear broader.

The tail end has also been remodelled by the design team, with the diffuser-look styling at the bottom now giving the Roadster an even more powerful appearance from the rear too. This is further emphasised by the trapezoidal exhaust tailpipes and the AMG-inspired darkened tail lights.

The exterior mirrors offer a larger surface area and feature LED indicators with a pronounced arrow shape, which help to create the distinctive night-time design of the SLK-Class. The larger mirrors mean that the new-generation Roadster now measures 43 millimetres wider.

The side-mounted rear aerial has also been reworked. It is now just 20 centimetres long, meaning that it blends into the car's silhouette more harmoniously. What's more, it no longer has to be removed when the vehicle is taken to an automatic car wash.

Light-alloy wheels in a new design and scintillating paint finishes

The range of light-alloy wheels has been virtually completely revised. Only the SLK 200 KOMPRESSOR continues to be fitted with the previous 16-inch wheels as standard (tyre size 205/55 R 16 V). The six-cylinder models ride on 16-inch and 17-inch light-alloy wheels in a new design (tyre sizes – SLK 280 front: 205/55 R 16 W, rear: 225/50R 16 W, SLK 350 front: 225/45 R 17 W, rear: 245 R 17 W). Furthermore, there is a choice of three new, dynamic wheel designs with mixed-size tyres for all engine variants.

"Palladium silver metallic" has been added to the range of paint finishes, as has "prehnite green metallic", a shade which is exclusive to the SLK-Class.

Driver-focused cockpit with sports steering wheel

Many of the interior's details have also undergone remodelling, and the interior has been refined as a whole by meticulous material selection. Particular care was taken to optimise the interior in such a way as to make it that much more driver-focused again. The centrepieces here are a new three-spoke sports steering wheel and a new instrument cluster. Four multifunction buttons can be found on both the left and right of the sports steering wheel on its horizontal spokes; a wood/leather steering wheel can be ordered as an option.

Facing the driver is a quite fascinating element in the form of the new instrument cluster, which has now been given a most exclusive and sporty touch thanks to the three-dimensionally shaped bezels of its dials. This, together with the new needles and the chrome surrounds for the clock and fuel gauge, lends far greater emphasis to the driver-focused design.

High-quality materials, new colours and new woods in the interior

High-tech and aesthetics also merge as one when it comes to the centre console's styling. The switches and buttons are now predominantly black in colour, resulting in a tidier, more harmonious appearance. That does not mean to say there is no room for a couple of highlights, however: a new chrome insert beneath the headunit catches the eye, combining with the new gleaming chrome fins of the cup holder and ashtray to produce an even classier feel.

The designers achieved an intriguing light and shadow effect by varying the cross-section of the trim strip on the passenger side to make it slightly convex. As a result, the dark and light zones change depending on the light, and the trim strip looks far more three-dimensional than before.

New "gullwing red" leather appointments will be available - reminiscent of the interior appointments in the legendary 300 SL gullwing model. The new nappa leather appointments in "natural beige" complement the new "pale burr walnut" and "black ash grain" wood trims perfectly.

Operation of the power windows has also been revised and optimised, and now features a push-pull control.

Telematics with voice control and MP3 connection

The new-generation SLK is accompanied by an entirely new generation of telematics componentry, boasting improved user friendliness, high performance and a host of new, handy functions. A hands-free facility using Bluetooth technology comes built in as standard, as does an aux-in port for connecting portable audio devices such as an iPod. A new media interface can also be specified as an option. The "Universal Consumer Electronic Interface" as it is known in the trade - or UCI for short - is more than just a new electronic connector in the glove compartment. The UCI interface also comprises a control unit which links up the external music storage device with the Roadster's electronic network and operating system. The great advantage of this is that the iPod's audio tracks appear in the instrument cluster and in the centre console's colour display, and can be simply called up by using the buttons on the multifunction steering wheel. The audio device's battery is recharged at the same time.

Exquisite, open-top sound experience

Customers can enjoy a unique listening experience, regardless of whether the vario-roof is open or closed, by opting for the new Harman Kardon® Logic7® sound system. The passenger compartment is filled by a rich surround sound for crystal-clear listening pleasure of an unprecedented standard for a roadster.

To achieve this tremendous advance in sound quality, the SLK-Class is equipped with the Discrete Logic 7 technology of the very latest Harman Kardon surround sound system. This achieves a level of audio reproduction that stays perfectly true to the original, whether it be a modern 5.1 multi-channel recording or in traditional stereo.

At the heart of the system is a high-performance amplifier with a formidable total output of 500 watts and a digital signal processor (DSP), whose advanced computing power regulates the frequency response to deliver a high-fidelity experience of the very finest calibre in the passenger compartment. To do this, the benchmark audio system automatically adjusts both the volume of the individual speakers and the intensity of the transmitted frequencies differently, depending on whether the roof is open or closed. Regardless of the ambient conditions therefore, both driver and passenger can savour a natural, perfectly balanced sound that is a joy to even the most discerning ears. Naturally, the system also includes speed-sensitive volume adjustment.

Harman Kardon uses only top-grade, specially developed aluminium-diaphragm speakers for the new surround-sound system in the SLK. The speakers' diaphragms comprise a triple-layer sandwich structure with an aluminium base. This strikes the optimum balance between rigidity and weight for the diaphragms, resulting in a sensational sound. A total of eleven speakers are installed in the SLK to transform the Roadster into a mobile concert hall.

Voice control with whole-word commands

Together with the new telematics generation, Mercedes-Benz is also offering the now enhanced LINGUATRONIC voice-operated control system as an optional extra for the SLK for the first time. This allows particularly straightforward operation of the telephone, audio and navigation systems using whole-word commands. In short, this means that drivers no longer need to spell out their commands, they simply say what they want to do when entering a destination, choosing a radio station or selecting a name from the telephone directory.

During the brief dialogue, the sound signal is digitised, transformed into a frequency spectrum and then analysed. During this process, the computer extracts certain characteristics from the sound signal at lightning speed. Doing so allows it to recognise the phonemes, which are the acoustic building blocks of any given language. The electronics analyse each sound, join the different phonemes together, cross-reference them with the contents of the phonemic dictionary stored in the system and also determine the acoustic plausibility of the word, all in a matter of milliseconds. In this way, the system itself is able to detect the finest nuances in pronunciation, meaning that it can distinguish, for example, between the words "town" and "down". In all, the phonemes for six different languages have been loaded into the system.

Mercedes-Benz makes an important contribution to traffic safety too with LINGUATRONIC, as drivers no longer need to take their hands off the wheel to operate the car phone or audio equipment. This lessens the driver's workload, making it easier to concentrate on what's happening on the road ahead. In 1996, Mercedes-Benz became the very first automotive brand to offer such a system in its cars. The very first generation of the system only required 512 kilobytes of computer memory - today, the system takes up over ten megabytes!

Trendsetter with unrivalled technology

As trendsetters and technology leaders, the SLK-Class Roadsters have long enjoyed the image of a modern cult car. The facelift measures for the 2008 version have clearly enhanced the car's looks, its specification and, above all, its dynamic potential. The familiar outstanding qualities have been retained, however; the vario-roof, for example, that transforms the Roadster into a coupé in 22 seconds, not to mention the comprehensive standard specification, including head/thorax sidebags, adaptive front airbags and two-stage belt-force limiters. The Roadster also offers the option of the unique AIRSCARF neck-level heating system, which is integrated into the seat backrests and emits a flow of warm air from openings in the head restraints. By so doing, the patented AIRSCARF system acts like an invisible scarf which keeps the occupants' head and neck snug and warm. The SLK-Class is thereby able to promise open-top driving pleasure all year round, even in the winter months.

A host of personalisation options

Once again, the new-generation SLK-Class comes with an extensive list of personalisation options to choose from. This includes a sports package with either 18" 6-twin-spoke light-alloy wheels or AMG 18" 5-spoke light-alloy wheels, accompanied by a sports suspension, 17" perforated brake discs, an AMG spoiler lip on the boot lid and anthracite surrounds for the headlamps. Inside, the leather seats, armrest, shift/selector lever and leather-trimmed steering wheel, all with red topstitching, inject a sporty flair, as do the seat belts with their red belt straps.

Apart from this, there is the designo range with its broad spectrum of exclusive colours and materials, which underscore the two-seater's sporty nature in style.

New sports engine in the SLK 350: A touch of racing track atmosphere

High-revving concept, added power and considerably lower consumption

Higher compression ratio and reengineered valve train

Sporty engine sound for emotion-charged acoustics

Seven-speed automatic transmission with automatic double-declutching

The goal set for the developers of the new-generation SLK was quite simply - even more sportiness, even more dynamism, even more emotion. To put it in a nutshell: even more driving pleasure. Making a mighty contribution to this are three redeveloped power units which stand out for their reduced fuel consumption, meaning lower CO2 emissions too. Besides this, both the four-cylinder engine in the SLK 200 KOMPRESSOR and the six-cylinder unit in the SLK 350 benefit from a substantial increase in output and torque too. 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 devoted particular attention to the V6 sports engine with high-revving concept, which is making its debut in the SLK 350. They were looking for much more than minor enhancements, substantially pepping up the six-cylinder unit's credentials by making extensive alterations to the mechanical setup. Three characteristics open up a new dimension in driving pleasure:

free-revving flexibility up to high engine speeds

a substantial increase in output

plus, a sporty sound that fires the emotions.

Brief spurts up to 7200 revs per minute

The 3.5-litre engine effortlessly races up to engine speeds normally well out of bounds for series-production engines in this displacement class. It attains its maximum output at 6500 rpm - if necessary, it is even capable of briefly spinning up to 7200 rpm. This outstanding free-revving flexibility has turned the six-cylinder unit into a thoroughbred sports engine.

Its sporty pedigree can be clearly sensed behind the wheel. The engine is a continuous presence: it comes across as bigger, more powerful than its predecessor and instantly responds to movements of the accelerator pedal, conjuring up a touch of racing track atmosphere in the cockpit without any trace of strain or agitation. Quite the contrary: the smooth running characteristics under the full spectrum of operating conditions have remained perfectly intact.

Output up by 24 kW/33 hp with fuel consumption cut by around a litre

The increase in output brought about by the reengineering also adds to the decidedly sporty feel. Although the displacement remains unchanged at 3498 cc, the V6 now musters up 224 kW/305 hp at 6500 rpm - some 24 kW (33 hp) more than its predecessor. Torque has been upped too (+ 10 Nm) and now peaks at 360 Nm at 4900 rpm. 350 Nm is on tap from as low as 2000 rpm, resulting in prodigious pulling power and exceptional performance. The SLK 350 dashes from zero to 100 km/h in 5.4 seconds, reaching a top speed of 250 km/h (electronically limited).

Despite the higher output and high-calibre performance, the SLK 350 sports engine burns considerably less fuel. With the six-speed manual transmission on board, combined fuel consumption is just 9.5 litres per 100 km, a remarkable reduction of 1.1 litres per 100 km; if the 7G-TRONIC automatic transmission is fitted, the sports engine limits itself to a mere 9.2 litres of fuel for every 100 km on the combined cycle - 0.9 litres less than previously. The cut in fuel consumption also lowers CO2 emissions by 23 g/km to 219 g/km on the automatic model (manual transmission: 227 g/km, a reduction of 28 g/km).

The key technical data for the SLK 350 sports engine

The sports engine in the SLK 350 is based on the previous V6 unit . The high-revving drive unit can be distinguished visually by the large red "V" on its cover. The all-important technical modifications are not visible however, and only make their presence clearly felt when the key is turned in the ignition.

New pistons for higher compression ratio and optimised efficiency

As the cylinder charge is restricted in naturally aspirated engines, the engineers at Mercedes-Benz resolved to boost the six-cylinder engine's output by increasing the rev speed and raising the compression ratio to 1: 11.7 (instead of the previous 1:10.7). Enhanced, weight-optimised pistons with a curved surface have paved the way for the increase in compression ratio, which improves efficiency and therefore saves fuel, particularly at partial throttle. To guarantee seamless valve operation, however, deeper pockets had to be milled for the valve seats . Reinforcements in the area of the piston pins give them the strength required to withstand the higher forces being exerted on them.

Single-stage intake manifold ensures improved cylinder charge at high revs

As the flap-controlled intake manifold used previously does not enable a high cylinder charge at high engine speeds, it has been substituted for a single-stage intake manifold to overcome this drawback. In order to optimise the intake manifold's design, the engineers elected to construct it from plastic. On the one hand, the core melt-out technique could be deployed with this material, meaning a high degree of design flexibility. Secondly, as plastic is a poor conductor of heat the new intake manifold stays colder than a die-cast part. So, the intake air does not heat up as much, which has a beneficial effect on the cylinder charge.

To address the inherent shortcomings of the single-stage intake manifold at engine speeds below 4000 rpm, the camshaft position has been advanced by 5 degrees of crank angle on both the intake and the exhaust sides. Since the altered flow characteristics of the new intake manifold allow the intake valves to be closed earlier, there was no need for a "sharper" camshaft to boost output. The excellent running quality has thus been retained at both idling speed and partial throttle.

Lightweight valves with sodium cooling and modified valve train

Higher engine speeds furthermore necessitated modifications to the valves and valve timing. Lightweight valves made out of ultra-high-strength and high-temperature-resistant steel are fitted in the new sports engine. The valve stems for the exhaust valves have a 3.4-mm bore and are filled with sodium to cool them down.

The distinguishing characteristics of any high-revving engine also include the conical springs that are deployed for the valve timing. As oscillations build up in the natural frequency of conventional cylindrical valve springs once a certain engine speed is reached, such springs are no longer able to close the valves properly. Conical springs, on the other hand, are able to reliably close the valves even at high engine speeds thanks to their heavily dampened natural vibration characteristics. The increased installation lengths of the conical springs, a revised intake port for optimum cylinder charging, as well as minor modifications to the cooling jacket all meant that a new cylinder head casting was needed.

Additional technical measures include stiffer cam followers as well as a tri-oval chain sprocket. Rather than being circular, this component has a barely noticeable triangular form which helps it to effectively counteract the chain sprocket vibrations that tend to increase at engine speeds above 6300 rpm. The tri-oval shape generates inversely phased amplitudes, thus reducing chain vibration and, in turn, the forces acting on it. The vibration damper on the belt pulley has also been adapted to make allowance for the modifications.

The exhaust system has been retained without any technical amendments. And thanks to the new engine management system, the sports power unit is still able to run on 95-octane premium fuel despite the higher engine speeds and output.

Emotive soundtrack underlines high-performance credentials

The capabilities of the new sports engine are not only evident in its power delivery; it also lets its presence be known by emitting a deliberately sonorous sound that lends acoustic emphasis to its high-performance character without ever being obtrusive. Yet, as the driving noise above 140 km/h is no louder than on its predecessor, a high standard of motoring comfort still comes guaranteed.

All that has changed is the tone. It is the noise emitted directly by the engine and a modified air cleaner that strikes a somewhat more aggressive note. Compared to the other SLK models, the engine makes a far more forceful impression, especially on the driver. This is down to an emotion-charged soundtrack, which generates the sort of noise associated with a powerful sports engine when the driver comes off the throttle. On models fitted with the 7G TRONIC automatic transmission, the engine management furthermore triggers an automatic double-declutching function during downshifts. Quite apart from producing an exceedingly sporty sound, this has practical benefits too: as double-declutching equalises the rotational speeds of the crankshaft and transmission, load-alteration effects are reduced, and the gearshift becomes more gentle and harmonious. The sporty acoustics therefore go hand in hand with a boost for safety.

Following the facelift, the engine line-up for the second generation of the highly successful SLK-Class will be completed by three further variants:

The four-cylinder supercharged engine produces an extra 15 kW/21 hp of output (135 kW/184 hp) thanks to the use of a modified engine management system, a more dynamic turbocharger and enhanced pistons. At the same time, maximum torque has been increased from the previous 240 to 250 Nm between 2800 and 5000 rpm. This propels the SLK 200 KOMPRESSOR from 0 100 km/h in 7.6 s (automatic transmission 7.9 s) and on to a top speed of 236 km/h (automatic transmission 232 km/h). Fuel consumption on the combined cycle has dropped by 1.0 litre to 7.7 litres per 100 km (automatic transmission: by 1.0 litre to 8.0 l/100 km). At the same time, CO2 emissions in six-speed manual models have been reduced by 27 g /km to 182 g/km (automatic: a reduction of 25 g/km to 190 g/km).

The SLK 280 has also undergone further improvement with respect to fuel economy and therefore CO2 emissions. It continues to produce 170 kW/231 hp from its displacement of 2996 cc, delivering 300 Nm of torque between 2500 and 5000 rpm. It takes 6.3 s to accelerate from 0 to 100 km/h (automatic transmission 6.2 s) and its top speed stands at 250 km/h. Fuel consumption has been cut by 0.4 l to 9.3 l/100 km (automatic transmission: by 0.2 l to 9.1 l), whilst CO2 emissions have been reduced by 11 g to 220 g/km (automatic transmission: by 6 g to 216 g/km).

The familiar 5.5-litre V8 powerplant is still at work under the bonnet of the SLK 55 AMG, developing 265 kW/360 hp and a peak torque of 510 Nm. The 0-100 km/h sprint is over in 4.9 seconds, the top speed is electronically limited to 250 km/h. The SLK 55 AMG has a combined fuel consumption of 12.0 l per 100 km with CO2 emissions of 289 g/km.

Sporty six-speed manual or seven-speed automatic

Standard specification for the three new SLK models includes a six-speed manual transmission, which provides fast, sporty gear changes coupled with supreme ease of shifting and lashes of fun at the wheel. The SLK 55 AMG comes with the AMG SPEEDSHIFT 7G-TRONIC, which has been specifically tuned for AMG models and features aluminium shift paddles on the steering wheel. As an alternative to the manual transmission, there is the option of a five-speed automatic transmission for the SLK 200 and, for the SLK 280 and SLK 350 sports engine models, the 7G-TRONIC automatic transmission with seven speeds or even the 7G-TRONIC Sport, with shift paddles on the steering wheel and shorter shift times.

In the interests of keeping fuel consumption low, a longer final-drive ratio was selected for the SLK 200 and the SLK 350 sports engine. This enables the SLK 350 sports engine model to break through the 100-km/h mark while still in second gear. Yet despite the longer ratio, it nevertheless manages to shave 0.2 seconds off the 0-100 km/h acceleration time of its predecessor.

New direct-steer system: Far sharper handling for scintillating cornering

Variable ratio for sporty, direct steering

Reduced steering wheel travel for crisp, precise steering

Improved active safety during evasive manoeuvres

The SLK feels perfectly at home powering along twisting country roads under clear blue skies, as it is here that motoring can be enjoyed at its very finest and purest. The fleet-footed cult roadster will now lap up sinuous stretches of tarmac with even more eagerness and precision, while inspiring an even greater sense of awe and pleasure in its driver: the latest generation of the two-seater powerhouse can be optionally equipped with a newly developed direct-steer system that blends agility and manoeuvrability with effortless parking and assured, forgiving steering characteristics at high speeds (standard in SLK 55 AMG).

The new direct-steer system was derived from the previous speed-sensitive power steering that Mercedes-Benz has offered for many of its models, including the SLK-Class. With this concept, the power that must be exerted to steer depends on the vehicle's speed - as the speed rises, so does the steering effort. In practice, this means low, comfortable steering forces when performing parking manoeuvres on the one hand, and, on the other, high safety when travelling at speed - for instance on the motorway - courtesy of increased steering forces for assured straight-line stability.

The steering ratio changes with the steering wheel travel

The new direct-steer system takes all of the positive attributes of the speed-sensitive power steering and adds to them a variable steering ratio, that changes depending on the steering angle.. In and around the central position, the steering has an indirect ratio for excellent straight-line stability, meaning a high level of handling safety. The direct-steer system's ratio starts to increase very rapidly at a steering angle of just 5 degrees, and feels quite direct from a steering angle of around 100 degrees. The result is a reduction in the required steering angle, as it is known in technical circles. In other words, relatively small turns of the steering wheel are sufficient for changing course. And, indeed, the number of steering wheel turns from lock to lock is reduced by around 25 per cent with the new direct-steer system.

Far more important than how the direct-steer system reads on paper, however, is what it actually feels like. Even at urban driving speeds, drivers do not need to turn the steering wheel a great deal, allowing changes in direction to be performed faster and with less effort. The effect of the direct-steer system is all the more impressive on winding rural roads. Small turns of the wheel are all that is needed to direct the vehicle, virtually eliminating the need to reposition the hands, even on tight bends; fast sequences of bends can be negotiated almost intuitively with relatively small steering movements – with assurance, precision and a healthy dose of driving pleasure. All of which translates into far greater agility.

This sharper handling can be measured in the form of high yaw amplification (in other words, the vehicle's steering response) at low to moderate speeds. The measurements also show that yaw amplification at high speeds is nevertheless low, meaning that the vehicle continues to respond to steering manoeuvres in a forgiving, assured manner.

Everyday drivers prefer the new direct-steering steering

This subjective positive impression is corroborated by the results of driving trials that Mercedes-Benz conducted with everyday drivers from different age groups and with varying experience. The outcome of these trials was as follows:

The new direct-steer system was rated as good as or better than the speed-sensitive power steering or standard steering systems across all criteria, which included controllability, steering precision, steering effort and the sense of safety.

The trial candidates found that the Roadster seemed far sportier with the direct-steer system.

Active safety when performing evasive manoeuvres increased objectively thanks to an average reduction in the required steering angle of 22 per cent. This eliminated the need for the drivers to reposition their hands on the steering wheel during the VDA evasive manoeuvre test.

The majority of drivers who took part in the trial favoured the direct-steer system overall.

Experts have also ascertained that, despite the more direct ratio at high speeds, the direct-steer system offers exactly the same supreme steering sensation and handling stability as previous steering variants.

An ingeniously simple mechanical solution

For all its remarkable properties, at the core of the new direct-steer system is nothing more than a simple steering rack. Its secret lies in the gearing impressed onto it. In the middle, it appears to be slightly undulating with changing flanks, towards each side it takes the form of teeth spaced at varying distances. Consequently, the change in steering ratio is achieved by mechanical means alone. Thanks to this smart solution, the engineers were able to dispense with the elaborate actuator units and complex sensor systems need for other variable-ratio steering systems. This means the direct-steer system is less susceptible to faults and lighter than these systems too. What's more, the steering's response to each turn of the steering wheel is always constant and therefore easy to anticipate, whereas other variable-ratio steering systems sometimes call for quick adaptation on the part of the driver in fast-changing situations.

SLK 55 AMG with direct-steer system and even more striking looks: Fine-tuning and yet more agility for the AMG eight-cylinder roadster

The SLK 55 AMG now makes an even more dynamic impression. The appearance of the sporty roadster reinforces even more emphatically the car's claim to being in a league of its own. The restyled front apron with a more pronounced V-shape, the modified Mercedes star, enlarged air dams and a black-painted transverse fin at the bottom ensure a distinctly masculine aura. Large, circular fog lamps with chrome surrounds are now positioned further outwards, enhancing the impression of width. The hot air from the integral engine oil cooler is vented via side outlets in the front apron. The exclusive SLK 55 AMG bodystyling also includes AMG side skirts, the muscular AMG rear apron with a black insert, along with the AMG spoiler lip.

New too are the projection-beam headlamps with dark surrounds and the exterior mirrors. The mirrors now have a larger surface to afford an improved view to the rear, whilst arrow-shaped LED indicator repeaters also ensure added safety. The AMG 18 inch light-alloy wheels in a multi-spoke design are more stunning than ever: painted in titanium grey and with a high-sheen star in the centre, they form an intriguing contrast when viewing the SLK 55 AMG side on. With a width of 7.5 and 8.5 inches at the front and rear respectively, the AMG light-alloy wheels are shod with size 225/40 (front) and 245/35 (rear) tyres. New, high-sheen AMG 18-inch twin-spoke light-alloy wheels with the same dimensions are furthermore available for the SLK 55 AMG as an option. Outstanding deceleration is guaranteed 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.

AMG eight-cylinder power unit for superior performance

The striking bonnet with its signature lengthways fins conceals the 5.5-litre AMG eight-cylinder engine delivering a maximum output of 265 kW/360 hp and 510 Newtonmetres of torque - figures which remain unrivalled in this segment. Phenomenal pulling power, instant responsiveness and the unmistakable AMG V8 sound mould the driving experience, together with the superlative performance: the two-seater rockets from zero to 100 km/h in just 4.9 seconds, reaches the 200 km/h mark in 17.5 seconds and has a top speed of 250 km/h (electronically limited). Power is transferred by the AMG SPEEDSHIFT 7G-TRONIC transmission with steering wheel gearshift paddles, which now boasts even greater agility: gear changes in the "S" (Sport) and "M" (Manual) driving modes are executed around ten per cent faster than before. This is not only thanks to the new components in the seven-speed automatic transmission, but also to the new engine and transmission management, which promises smoother gearshifting too.

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-steer system. The grip area is specially contoured and lined with perforated leather, while the vertical spoke is embellished with a silver-coloured insert. Two aluminium AMG shift paddles allow manual gear selection.

The AMG instrument cluster with a 320 km/h speedometer scale, silver/red needles and AMG lettering also sports a new look, with the new graphics ensuring that vehicle speed and rpm are even more clearly legible. In "M" mode, the AMG main menu is able to display the currently selected gear including an upshift recommendation, as well as the engine oil temperature, the battery voltage or the RACETIMER. The AMG sports seats with their special upholstery layout feature pronounced side bolsters for optimising lateral support when cornering at speed; Alcantara inserts in the shoulder areas improve this support even further. Fine nappa leather upholstery makes up part of the standard appointments on the SLK 55 AMG. It is available in a choice of four attractive colours, including the combination black/gullwing red which is a new addition to the range.

Performance package for the driver with racing ambitions

The list of optional extras includes the AMG performance package: developed by the AMG PERFORMANCE STUDIO, this package incorporates technical components offering yet greater performance and durability. The result is an even more thrilling driving experience for sports car enthusiasts who sometimes like to put their AMG model through its paces on the racetrack.

The AMG performance package for the SLK 55 AMG comprises:

AMG high-performance braking system with composite brake discs at the front wheels

Internally ventilated and perforated composite brake discs, size 360 x 32 mm, with six-piston fixed callipers at the front

Internally ventilated and perforated brake discs, size 330 x 26 mm, with four-piston fixed callipers at the rear

AMG 18-inch multi-piece light-alloy wheels in a twin-spoke design, size 7.5 x 18 with 225/40 R 18 tyres at the front and size 8.5 x 18 with 245/35 R 18 tyres at the rear

AMG performance suspension

AMG performance steering wheel with smaller diameter, flattened lower section and silver-coloured aluminium shift paddles (plus aluminium trim element)

AMG carbon-fibre trim in the interior

With the exception of the AMG high-performance composite braking system, all the components of the AMG performance package can also be ordered individually for the SLK 55 AMG