THE boffins at AMG’s Affalterbach headquarters have proved it: eight into SLK does go. And how! If ever there had to be justification for the little two-seater Merc’s SLR McLaren looks, it’s this car. With a 265 kW normally aspirated V8 stuffed into the engine bay, the maus has become a muscle car. The SLK 55 really flies. And not in the genteel way you might anticipate from experience with its more modest siblings. This is rip-roarin’, black-stripin’ performance that would do a Yankee muscle car proud…
Open that long bonnet with the psuedo F1-style nose running down the centre, and you’re left in no doubt: the dominant aspect of the SLK flagship is the engine. Muscle maus CAR January 2006 119 Performance that would do a Yankee muscle car proud Hand-built by a single technician, it’s an automotive work of art. No compressor or turbos to queer the pitch here, just an alloy block V8, a five-bearing crank, a pair of threevalve heads, a displacement of 5 439 cm3, and a microprocessorcontrolled petrol injection system working under plain ol’ atmospheric pressure.
The power-unit is laced with high-tech inspiration from the race track, boasting extra-light forged aluminium pistons, oil-spray nozzles to cool the piston crowns, variable camshaft timing, a special twin-pipe intake system, and a variable intake manifold.
In tandem with the no-nonsense power-unit is Mercedes-Benz’s ultra-high-tech seven-speed 7GTronic autobox, specially tuned for this application, and carrying the AMG-Speedshift label. There are shift buttons on the wheel, and a “Tipshift” facility on the lever to operate a special manual driving programme, and the torque converter features lock-up from first gear to minimise power-loss.
To deliver all this dynamic capability to the road, there’s also specially-tuned AMG sports suspension. The gas struts and anti-roll bars, front and rear, are unique to the SLK 55 AMG. So are the brakes – internally ventilated grey cast iron 340 mm discs with six-piston calipers in front, and solid 330 mm units with four-pot calipers at the rear. Control systems such as ESP, ASR and Brake Assist have been fine-tuned to complement the car’s sporty driving dynamics.
All this is clothed in a bodyshell that doesn’t look too different from the other SLK models. But what immediately sets the car apart is its special AMG alloy wheels, reminiscent of those of the SLR McLaren, in different widths, front and rear. The test car’s 18×7,5J fronts were shod with 225/40 Pirelli P Zero Rossos, the 8,5J rears with 245/35s. And then there’s the exclusive AMG front apron, with its slot for an oil cooler and round fog lamps with chrome bezels, the black-painted cross-fins in the split grille, the gills on the bonnet, the side outlets through which the air exiting from the oil-cooler is expelled… More subtle tweaks are the darkened glass covers on the tail-lights, and the two sets of twin tailpipes peeking through the rear valence.
Inside, the finish of the snug twin-seater cockpit has been taken up a notch. Seats, door panels and armrests are covered in nappa leather. The multi-function wheel is adjustable for rake and reach, and the electrically adjusted chairs are a special AMG design, with prominent bolsters to provide optimum support, and Alcantara inserts in the shoulder area to provide extra grip in fast cornering manoeuvres.
And there are all the usual luxury touches you’d expect in a car with this price tag. As in lesser SLKs, you get a top-notch Harmon Kardon audio system in the hang-down section of the facia, as well as satellite navigation with video, and an onboard ’phone facility (with Bluetooth capability). There’s climate control, as well as Headscarf, the effective top-down neck-warming system,
And there to shield your head in inclement weather is the Vario electric roof, almost as much a feature of the SLK 55 AMG as that punchy engine. Sure, it might raise the car’s centre of gravity a fraction, but when its closed – at the touch of a button, of course – it’s as secure as a fixed steel hardtop.
Fire up the V8, and it idles with a throaty burble that promises good things to come. Blip the throttle and there’s a muscular roar from the quad tailpipes. Accelerate away and you’re immediately aware of the huge reserves of torque, the car surging forward with alacrity after cruising virtually at tickover in the higher gears. Select the manual mode, and the seven-speed ’box hangs on to the chosen ratio, right up to the 6 500 red line and a fraction beyond, where the rev-limiter intervenes to stop anything untoward.
There’s less lag than with some other autoboxes with button-activated shifts, the SLK 55 feeling like a four-wheeled motorcycle as it sprints through the closely-spaced ratios. In addition to the lock-up feature, AMG says the gearbox’s changes are 35 per cent faster than in a standard 7GTronic. We tried both manual and auto shifting in our acceleration testing, and though manual changing was more satisfying, we found the auto mode consistently quicker. Our best runs, which resulted in a zero to 100 time of 5,22 seconds and a standing kilometre in 24,20 seconds, were achieved with the electronic brain doing the changes. The two-way averaged top speed, nominally limited to 250, came out a smidgen higher, at 252 km/h, achieved in the 0,82:1 sixth gear.
Switching out the ESP – essential for the best performance off the line – provides tyre-smoking getaways. But leaving it on is the best policy in normal, quick driving. The AMG-tuned system intervenes a fraction later than normal set-ups, thus preserving sportscar- style driving enjoyment together with a “safety net”. Out on our favourite twisty road, we found the SLK 55 would hang on well, but, with that comparatively heavy lump up ahead, the front tends to push at the limit. Booting it out of slower corners has the back wheels wanting to unstick, and, with the ESP switched out, lurid tail-out slides are possible. The rack and pinion steering is communicative but a touch heavy.
The test car weighed in at a quite hefty 1 607 kg with our equipment in place, but the AMG-uprated braking system was well up to the job of reining it in from high speed. In our 10-stop emergency braking test, the SLK 55 averaged 2,81 seconds from 100 to rest, without the slightest sign of discomfort. In normal driving, the pedal had good feel and was easy to modulate.
Fuel consumption is impressive for a fairly heavy-bodied V8 bruiser – the SLK 55’s CAR fuel index worked out at 12,54 litres/100 km, which is virtually the same as our estimated figure for a Porsche Boxster S Tiptronic. The test result suggests a respectable range of 558 km on a 70-litre tank of unleaded.
Test summary
The biggest plus about Mercedes-Benz’s compact sports two-seater has always been its folding steel roof, a facility that gives owners the choice of a breezy open car for sunny days, or a snug coupé for less pleasant weather. But, in AMG form, for the first time, the SLK’s performance abilities outshine the high-tech roof. The V8 powerhouse turns the car into a muscley road-burner that gives as good as it gets away from the traffic lights. And, of course, there’s still the funin- the-sun capability if you’re in a more relaxed mood.
