In aesthetic terms, Mercedes aftermarket tuners tend to fall into one of two categories: mild or wild. Brabus and Carlsson support the former school of thought, while Lorinser, MAE Design and Asma Design are proponents of the latter.
I expected no less than simple elegance when I came to see Carlsson’s take on the new SLK, and I was not disappointed. As usual, their designer, Rolf Schepp, has done a fine job of getting a feel for the standard car’s styling, and then seamlessly blending in the Carlsson house style for a relatively subtle but distinctively elegant result.
On the SLK, a designer has to be extra careful with bold design motifs that can become crowded if more than one appears together, or simply out of proportion if applied for their own sake.
Sound is important in a sports car, and the SLK presses all the right buttons here.
A case in point is the SLR-style nose treatment nose on the previous R171 SLK. The bulbous nose cone sat very uneasily on the front of the much shorter and narrower SLK. And when the AMG body styling was applied with its various larger intakes, the end result appeared far too fussy on a car of such small physical dimensions.
The latest R172 SLK has a much more sculpted look, with pronounced haunches that give it Coke-bottle rather than wedge-shaped flanks. This helps to balance the design when seen from different angles. But like so many production cars, in its base form with standard wheels, the SLK looks unfinished and just cries out for bigger wheels and wider rubber. The new, more muscular looking SLK takes to subtle body styling enhancements much better than its predecessors.
The optional AMG body styling ties in beautifully with the curved rear haunches, giving the car a more muscular look. Carlsson uses the AMG package as its base, adding a new front spoiler to which you can also fit the company’s RS front bumper lip. The nine-piece, electro-polished stainless steel mesh kit for the grille and underbumper intakes looks particularly good on a black car, giving the front end a more classically sporting look.
At the rear, the new diffuser insert, which can be ordered in carbon fiber, has cutouts for the four big polished exhaust outlets. The small bootlid trailing edge spoiler is the finishing touch, and adds a bit of downforce to counter lift over the rear axle at speed.
Fitted with 235/35ZR19 and 265/35ZR19 rubber, the 8.5- and 9.5x19 Carlsson 1/10 Graphite Edition alloy wheels fill out the arches. Together with the 1.2-inch ride height drop provided by the sport spring set, they help to give the car its broader, more hunkered down stance.
The latest turbocharged 1,796cc four-cylinder is the best four-pot petrol engine Mercedes has ever made. Smooth, powerful and economical, in the SLK in particular it’s a hoot to drive. Sound is important in a sports car, and the SLK presses all the right buttons here. On the intake side, the factory-tuned resonance chamber gives the induction system the acoustic properties of a brace of carburetors when you use the throttle in anger. Carlsson’s stainless rear exhaust silencer helps to reduce backpressure and gives the exhaust a deeper, more mellifluous tone to match the gurgling induction roar.
For the tuners, the downside of the new motor is the Siemens ECU, which has pretty robust security protocols. For now at least, tuners have had to resort to using an external piggyback ECU to intercept the signals between the factory ECU and motor. The Carlsson C-Tronic unit performs this task in real time by tricking the Siemens unit into thinking that the information received is within normal operating parameters.
As manufacturers look ever more closely at controlling costs, the presence of components with significant performance headroom that can be taken up by the aftermarket tuners is dwindling. In the case of the SLK, the factory intercooler does not have far to go before it reaches its limit, so a 10 percent more efficient unit is part and parcel of Carlsson’s CB25 S engine upgrade kit. Apart from allowing a 15 percent higher boost pressure over the stock 1.2 bar, it also benefits reliability by helping to limit the thermal stress imposed on the uprated engine.
The result of these modifications is an increase in power from 204 hp at 5,500 rpm to 239 hp, while torque goes up from 229 lb-ft between 2000 and 4300 rpm to 273 lb-ft. The higher peak figures are attained at the same engine speeds.
As the ECU remapping also affects the response of the e-gas throttle, there is more to the change in driving characteristics than just the power and torque increase. In Sport mode, the already responsive engine feels like it has just had its claws sharpened, delivering its newfound output with even more verve and eagerness. Couple that to the more sporting exhaust note, and you have a small roadster that gives you a fine stereo effect from both induction and exhaust when you’re wringing it out on a twisty road.
You feel the extra torque more than the power because you use it all the time, especially around town and exiting bends. That same twisty road also reveals that the extra grip provided by the bigger tires and the enhanced stability of the lowered suspension are running ahead of the comparatively modest power increase. It feels like the chassis upgrade would only come into its own when paired with the more powerful V6.
With clients becoming more enlightened to the joys of bespoke interior trim, Carlsson was able to go some of the way with this car, which was bound for a customer in Thailand. The black and orange interior trim is extroverted to say the least. The headrests, side bolsters, and door inserts are covered with orange leather, while the seat inserts have three black panels each, with a quilted effect highlighted by orange cross-stitching.
In a reverse effect, the orange door inserts are set off with black quilt-effect cross-stitching. The same colors are used on the Carlsson gear knob, whose black leather gaiter has orange stitching highlights.
Finishing touches are the orange edging on the black Carlsson floor mats with larger than normal Carlsson logos, the alloy pedal set and footrest and the stainless steel doorsill entrance plates. While this interior color scheme might not be to everyone’s taste, the quality of the workmanship is undeniably top-notch.
Mercedes claims the new SLK has been a big hit with customers. The fact that they managed to deliver the first cars this summer has certainly helped. Carlsson’s modifications really make the car look complete, and the admiring glances we received from other drivers and people on the street when driving to and from our photo location certainly underlines that.
Carlsson SLK CB25 S
Longitudinal front engine, rear-wheel drive
1.8-liter I4, dohc, 16-valve, turbocharged. Carlsson CB25 S upgrade kit, sport exhaust, C-Tronic piggyback ECU
Lowering springs (1.2 in.)
Wheels and Tires
Carlsson 1/10 Graphite Edition alloys, 8.5x19 (f), 9.5x19 (r)
Dunlop SP Sport Maxx 235/35 (f) and 265/35 (r)
Carlsson front spoiler and RS carbon lip, stainless steel grille/intake mesh, rear diffuser insert, bootlid lip spoiler
Custom black and orange leather interior trim with contrasting stitching, Carlsson alloy pedal set and gearknob
Peak Power: 239 hp
Peak Torque: 273 lb-ft