2009 Mercedes-Benz SLK-Class SLK55 AMG Road Test

2009 Mercedes-Benz SLK-Class SLK55 AMG Road Test

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  • Pricing & Specs
  • Road Tests (1)
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2009 Mercedes-Benz SLK-Class Convertible

(5.4L V8 7-speed Automatic)


Stupendously powerful V8, addictive engine and exhaust notes, retractable-hardtop versatility, capable handling, brilliant voice-command functionality.


Mandatory automatic transmission, miserable stereo, COMAND interface is a hassle without voice commands.

My Friends All Drive Porsches. I Must Make Amends

So you've got yourself a dilemma. You're in the market for a high-end roadster, but your country club's parking lot is so full of Boxsters and 911 Cabriolets, it makes you wonder if Porsche owns the place. Not that you'd really consider those cars anyway -- they're soft-top only, and besides, they sound like lawnmowers. But what should you buy instead? Here's an unconventional answer: a 2009 Mercedes-Benz SLK55 AMG.

Why unconventional? For one thing, the SLK55 is stuck with an automatic transmission. Not an automated-clutch manual, mind you, but an old-fashioned slushbox that doesn't even blip the throttle on downshifts. Most competitors offer stick shifts, and Porsche's new dual-clutch PDK tranny punts the Benz's slow-witted seven-speed into the Schwartzwald. Furthermore, Mercedes isn't exactly renowned for making world-class sports cars, though this AMG drop top does corner athletically when you give it the crop.

But the SLK55 has more than just a slick retractable hardtop to lord over its Porsche compatriots. In a deliciously vulgar rejection of the "less is more" approach, Mercedes has gone and wedged a gigantic hand-built 5.4-liter V8 under this Miata-sized hooligan's hood. That's the same displacement as the top-of-the-line V8 in Ford's F-150 full-size pickup; what's more, the F-150 would actually benefit from an engine swap, as the SLK55's mill makes 45 more horsepower and 11 more pound-feet of torque. In other words, this is one bad little Benz. Put your foot down at any speed and the SLK55 hurtles forward like a runaway locomotive, quad exhaust tips belting out an intoxicating eight-cylinder symphony.

When you're not feeling felonious, the SLK55 makes for a surprisingly civilized companion, boasting well-shaped seats, a tolerably firm ride and a refined top-up demeanor marred only by intrusive road noise over coarse surfaces. It's an adroit double act that recalls the SLK55's big brother, the SL63, which costs twice as much. The SLK55 still doesn't come cheap, but our nicely optioned tester's $72,545 sticker isn't entirely unreasonable for a wickedly fast V8-powered luxury roadster. Lackluster transmission notwithstanding, we strongly recommend asking the Lord to buy you this Mercedes-Benz.


The rear-wheel-drive 2009 Mercedes-Benz SLK55 AMG is powered by a 5.4-liter V8 that pumps out 355 hp and 376 lb-ft of torque. A seven-speed automatic with manual control is the only available transmission, and it's the SLK55's weakest link. Manual downshifts aren't rev-matched, and overall responsiveness is disappointing. At the test track, our SLK lunged from zero to 60 mph in a fleet 4.9 seconds and blasted through the quarter-mile in 13 seconds flat at 108.8 mph. It might have been quicker still with grippier tires, as wheelspin was a limiting factor in the first two gears.

On the road, the SLK55 AMG is essentially a modern-day Shelby Cobra, albeit with a thick layer of luxury slathered on top. The Benz's basic formula comes straight from that icon's playbook: Start with a capable compact roadster, stuff it to the gills with a honking V8, sharpen the suspension and proceed to scare the living daylights out of people. Cars don't get much more thrilling than a top-down SLK55 at full throttle, engine roaring, landscape blurring, speedometer needle spinning clockwise at an impossibly rapid rate. With an as-tested weight of 3,474 pounds, the feature-laden SLK55 is hardly an elemental sports car, but only the most depraved horsepower fiend will find its acceleration wanting.

When the straights turn to curves, the SLK55 remains in its element. The new-for-2009 "Direct Steer" variable-ratio steering isn't hyper-responsive, but it's crisp enough, and there's a reassuring heft that builds as cornering loads increase. Body roll is negligible, and there's plenty of grip for spirited driving on public roads. However, we found this short-wheelbase Benz was best at nine-tenths or less -- push it to the limit and the SLK55 gets squirrelly.

Our best panic stop from 60 mph in the SLK55 took 115 feet, which isn't particularly impressive for this class. Nonetheless, the Benz's binders feel imperturbable under all conditions -- "autobahn brakes," as our track driver put it. Against EPA fuel-economy ratings of 14 mpg city/22 highway and 17 combined, we averaged just over 17 mpg -- remarkable considering that the gas pedal was frequently pinned to the floor.


The 2009 Mercedes SLK55 AMG greets you with up to 15 rapid-fire econocar-style beeps when you twist the key. We're surprised Mercedes hasn't taken a page out of BMW's book and gone with a mellifluous chime instead. Once you're under way, the hardtop provides superior insulation from the elements, but road noise can be objectionable. With the top down, there's little cowl shake to speak of, and wind buffeting at highway speeds is easily mitigated by raising the windows.

The SLK55's ride is notably taut, yet impact harshness is mostly absent, a trademark of German luxury cars. The seats are 911-like -- they don't look like much, but somehow they manage to provide exemplary support and adequate long-distance comfort. You can forget about suavely hanging your arm over the windowsill, though, thanks to the SLK's prohibitively high beltline. Oddly, legroom is limited on the passenger side, but our lankier editors had no problem getting comfortable behind the wheel.


The SLK55's primary gauges are clear and easily read at a glance. Climate controls are idiot-proof: two big rotary knobs control fan speed and airflow, and well-labeled buttons take care of the rest. On the downside, sound quality from the upgraded Harman Kardon Logic 7 stereo is abysmal -- the only speakers aft of the seats are two tiny tweeters in the upper center storage bin, creating a forward-biased sound stage, and the sound itself is a weak and muddy mix of indistinct lows and tinny highs, especially with the top down.

The familiar COMAND interface -- which controls audio, navigation and Bluetooth functions -- employs a dash-mounted four-way keypad that can be a bear to operate. However, our test car's optional enhanced voice control system was a revelation. When you pull the dedicated stalk on the steering column, a list of possible voice commands pops up on the display screen; say one aloud and COMAND reliably complies. Virtually every common function is covered, so we mostly just told the Benz what to do rather than mess with the buttons and menus ourselves. Imagine telling the navigation system your destination on the fly, then canceling it once you're close by simply pulling the stalk and saying, "Cancel route guidance." It's a brilliant system, and we think it points to a brighter automotive future in which the maddening complexity of modern multimedia interfaces will be neutralized by well-executed voice-command functionality.

In our real-world usability tests, the SLK55's respectable 9.8-cubic-foot trunk proved adequate for a two-person weekend getaway, but not much more than that. While our standard suitcase fit fine, little else would have fit alongside it. We had to remove the woods from our golf bag in order to squeeze it in; owners may well decide to save themselves the hassle and let the clubs ride shotgun.

Design/Fit and Finish

The 2009 Mercedes-Benz SLK55 gets the AMG exterior treatment, and we like its aggressive yet restrained look. The hardtop is stylishly integrated, whether raised or lowered. Inside, the dashboard layout isn't very sporty, but materials quality is good save for the sun visors, which are made of hard plastic and inexplicably perforated. Our test car's only notable build issue was the failure of the tachometer's 2,250-rpm hash mark to illuminate.

Who should consider this vehicle

Luxury roadster shoppers who want V8 vigor and a retractable hardtop in a pint-sized package -- and don't mind settling for a slushbox.

Others To Consider
BMW M3 Convertible, Chevrolet Corvette Convertible, Porsche Boxster S.

The manufacturer provided Edmunds this vehicle for the purposes of evaluation.

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