When automakers start increasing power in their products, the current fashion is to throw a turbocharger on it, mainly because there’s an added bonus of improved efficiency too. Fewer and fewer are going the classic musclecar route of throwing extra displacement at a problem. Witness the monster M cars from BMW or the latest flock of mid-range S and RS beasts from Audi… one or two turbos, or in Audi’s case, a supercharger.
|1. A 5.5L V8 engine delivers best-in-class power of 415 hp and 398 lb-ft of torque with a 4.5 second 0-60 time.
2. A $4,750 AMG Performance Package adds unique wheels, custom suspension tuning, a 174 mph top speed and a limited slip differential.
3. With SLK models starting at $42,900 the AMG version is $67,990 plus extras.
Knowing that Mercedes-Benz’ in-house tuner AMG is moving all of its products back to forced induction over the next few years, only the C63 and now SLK55 remain unfettered by boost-adders. While there’s something to be said about the right-now torque of the twin-turbocharged monsters, the vocal appeal of the regular V8 is something to be appreciated. They roar at speed and almost have that lumpy idle like big-block monsters back in the day. Very un-European, but that’s why it gets our blood pumping.
BIG V8: NOW WITH EVEN MORE POWER
The 5.5-liter V8 found in the SLK55 AMG keeps the same displacement, but is thoroughly reworked to provide more power, torque and even improve fuel efficiency. The engine is now a DOHC design with 32 valves plus direct injection, delivering 415 horsepower and 398 lb-ft of torque, up 60 and 22 respectively. It’ll also rev higher too, with peak power delivered at 6800 rpm instead of 5750.
And it benefits from AMG’s first attempt at cylinder management, meaning it’ll shut off a full bank of four cylinders under low load to save fuel. Combined with a seven-speed automatic transmission that defaults to an efficiency setting and a system that shuts the engine off at stoplights, and the SLK55 AMG isn’t the gas-chugging monster you might expect. Its official ratings of 19 mpg in the city 28 on the highway are pretty remarkable.
Worried that all these efforts to save the planet have made the SLK55 a little soft? Think of it more as offsetting the damage done by tire smoke and triple-digit speeds. It’ll rip through the 0-60 mph run in only 4.5 seconds before topping out at an electronically-limited 155 mph.
ADD EVEN MORE AMG
There has been a little weight gain of about 100 pounds between generations, but that hasn’t affected its performance. AMG-tuned products are usually more muscle than grace, but the SLK55 is pretty good at turning too, thanks in part to a lower and stiffer suspension compared with the plebeian models, not to mention 235/40/R18 tires up front with wider 255/35/R18s out back. The optional AMG Performance package found on our tester also adds a limited-slip rear differential, unique multi-spoke wheels, an even more enjoyable suspension tune and ups the speed limiter to 174 mph. It’s not cheap at around $4,750, but we like the results.
Compared with the SLK250 we drove last year, the steering is heavier and more direct, although it’s no Porsche when it comes to feel through the AMG-designed wheel.
Thankfully, it loses the weird bobble at lower speeds that makes the base car not feel entirely connected. Also, the enormous brakes do their job admirably, although conditions weren’t ideal during our time with the SLK55 to determine their resistance to fade on track.
INTERIOR: ADDED LUXURY AND SPORT
The sport seats do a much better job of holding you in place than those in the regular SLK thanks to bigger bolsters. Plus, they’re covered in leather with contrasting stitching… but they don’t sacrifice the AIRSCARF ventilation, which is great at extending the top-down season.
The rest of the cabin is handsome, but with significantly more toys and technology. With both the Premium and Multimedia packages included, the long list includes things like hard-drive-based navigation with a 10GB music ‘register’, an 11-speaker harman/kardon sound system, heated seats, a larger seven-inch color display and plenty more.
Exterior upgrades also included the optional lighting package with active bi-xenon headlights, adaptive highbeams and headlight washers. Those are in addition to the more aggressive front fascia and grille, the lower side valances, a ‘subtle’ decklid spoiler, and AMG’s signature quad exhaust pipes out back. While the SLK can never be considered pretty, the changes are reasonably dramatic.
Top-down motoring is available in about 20 seconds, which also helps the car’s lines since the roof can look a little awkward from some angles. It also gives that wonderful exhaust note an easier chance to be appreciated.
When it comes to competitors, the Porsche Boxster S and Audi TT-RS are the usual suspects, although neither one comes close to delivering the AMG’s 400-plus horsepower. The $61,000 Boxster remains a scalpel against the SLK55’s machete, but its 315 horsepower and optional PDK transmission give it nearly the same acceleration numbers. The TT-RS splits the two with 360 horsepower but its all-wheel drive system means it only takes 4.1 seconds to hit 60 mph. Sadly, however, the drop-top isn’t available this side of the Atlantic. It’s also the oldest and least expensive option here, coming in fully loaded about $3,000 below where the SLK 55 AMG starts.
Speaking of which, our tester’s $67,990 base price ballooned remarkably into a $78,300 machine, which means you’d better be seriously invested in your performance. The AMG badge does buy a lot of credibility, and it’s absolutely the best effort yet trying to inject some excitement into the baby ‘Benz roadster. Still, the SLK55 is more about looking fast (and sounding it) than actually going fast.