The 2012 Mercedes-Benz SLK55 AMG emerged as a pinnacle of performance within the esteemed SLK lineup, staking its claim as the most potent SLK variant ever conceived. This model year marked a significant leap, primarily fueled by the introduction of a revolutionary AMG 5.5-liter V8 engine. This powerplant wasn’t just about raw power; it ingeniously incorporated cylinder shutoff technology, achieving a harmonious balance between exhilarating performance and optimized fuel consumption. With a formidable peak output of 415 horsepower and a commanding 398 lb-ft of maximum torque, the 2012 SLK55 AMG was engineered to demonstrably outclass its rivals in the competitive high-performance roadster segment. Ensuring a dynamic driving experience, the vehicle was equipped with an AMG sports suspension system featuring Direct-Steer, Torque Vectoring Brakes, and a sophisticated 3-stage ESP®, complemented by the robust AMG high-performance braking system. The anticipation culminated in early 2012 as the 2012 SLK55 AMG made its grand debut in U.S. showrooms.
As part of the third generation of the SLK, initially launched in June, the AMG variant immediately commanded attention with its striking aesthetics. Distinctive AMG light-alloy wheels and exclusive AMG body styling, complete with an AMG spoiler lip and dual chrome-plated twin tailpipes at the rear, accentuated the classic roadster silhouette while injecting a pronounced athletic vigor. The expressive design language of the 2012 SLK55 AMG is both visually arresting and instantly recognizable, signaling its high-performance pedigree.
The SLK55 AMG perfectly encapsulates AMG’s new brand ethos, “Driving Performance.” Within the compact high-performance Roadster category, it stands unmatched, seamlessly merging palpable driving dynamics, superior sportiness, cutting-edge technology, and surprisingly efficient fuel consumption. The 2012 SLK55 AMG achieves a blistering zero to 60 mph acceleration in just 4.5 seconds, and confidently reaches an electronically limited top speed of 155 mph. This blend of raw power and refined engineering places the 2012 AMG Mercedes-Benz SLK55 AMG in a league of its own.
| 2012 SLK55 AMG | |
|---|---|
| Displacement | 5,461 cc |
| Bore x stroke | 3.86 in x 3.56 in |
| Compression ratio | 12.6 : 1 |
| Output | 415 hp at 6,800 rpm |
| Max. torque | 398 lb-ft at 4,500 rpm |
| Engine weight (dry) | 412 lbs |
| Acceleration | 0 – 60 mph 4.5 s |
| Top speed | 155 mph** |
| * provisional figures; ** electronically limited |
Setting new benchmarks for fuel efficiency in the realm of V8 engines, the 5.5-liter powerhouse masterfully combines frugal fuel consumption with potent power delivery, all while emitting the signature, resonant exhaust note that only a large-displacement eight-cylinder engine can produce. This achievement aligns perfectly with AMG’s “Performance 2015” strategy, demonstrating a commitment to continually reducing fuel consumption and emissions across new models, while simultaneously elevating the brand’s core promise of “Driving Performance.” The M152 engine in the 2012 AMG Mercedes-Benz SLK55 AMG is a testament to AMG’s dedication to both performance and environmental responsibility.
The Heart of the Beast: The New Naturally Aspirated V8 Engine
The newly developed M152 naturally aspirated eight-cylinder engine shares a close lineage with the AMG M157 5.5-liter V8 biturbo engine, which debuted in 2010 and powered models like the E63 AMG, CLS63 AMG, S63 AMG, and CL63 AMG. Numerous design elements are shared between these engines, including displacement, bore and stroke dimensions, cylinder spacing, ECO stop/start system, and direct gasoline injection technology. However, the M152 distinguishes itself from the M157 through several key modifications, including redesigned intake air ducting, new cylinder heads, a refined valve drive, an adapted oil supply system, and an optimized crankcase. These enhancements were specifically tailored for the unique demands of the SLK55 AMG, focusing on responsiveness and efficiency in a roadster application.
The distinctive AMG light-alloy wheels of the 2012 SLK55 AMG enhance its sporty and aggressive stance, reflecting the vehicle’s high-performance capabilities.
Advanced Technology: An Exclusive Combination
The M152 engine in the 2012 AMG Mercedes-Benz SLK55 AMG is a showcase of cutting-edge automotive technology. It boasts an unparalleled combination of features, including direct injection operating at an immense pressure of 2,900 psi, spray-guided combustion, and piezo injectors. These are integrated with map-controlled cylinder shut-off, an all-aluminum crankcase featuring “spectacle” honing, four-valve technology with continuous camshaft adjustment, a high compression ratio of 12.6:1, a stop/start system, and sophisticated generator management. All these technologies work in concert, enabling the engine to rev beyond 7,000 rpm while maintaining exceptional thermodynamic efficiency. This efficiency is crucial for achieving both remarkable fuel economy and reduced exhaust emissions. The utilization of a large-displacement, naturally-aspirated eight-cylinder engine equipped with cylinder shut-off adeptly resolves the inherent conflict between high power and torque delivery and the imperative for low fuel consumption.
AMG Cylinder Management: Efficiency Redefined
The AMG Cylinder Management system, a proprietary development by Mercedes-AMG, is pivotal in enhancing fuel efficiency. Under partial load conditions, cylinders two, three, five, and eight are deactivated, significantly curtailing fuel consumption. This technology draws inspiration from similar systems employed in the high-output 750-hp V8 engines used in Formula 1 racing, where efficiency is also paramount, even under extreme performance demands.
The cylinder shut-off functionality engages across a broad engine speed range, from 800 to 3,600 rpm, provided the driver has selected the “C” (Controlled Efficiency) transmission mode. The AMG main menu, displayed within the instrument cluster, provides real-time feedback to the driver, indicating whether cylinder shut-off is active and whether the engine is operating in four or eight-cylinder mode. Even in four-cylinder mode, a substantial 170 lb-ft of torque remains available, ensuring ample power for everyday driving scenarios and responsive acceleration. When increased power is demanded and the driver moves beyond the partial load range, cylinders two, three, five, and eight are seamlessly reactivated. This transition from four to eight-cylinder operation is instantaneous and imperceptible, preserving passenger comfort. At an engine speed of 3,600 rpm, the activation process is completed in a mere 30 milliseconds, showcasing the system’s responsiveness.
The AMG instrument cluster in the 2012 SLK55 AMG clearly indicates the active cylinder mode, displaying “ECO4” when the fuel-saving four-cylinder mode is engaged.
Valves, Fuel, and Ignition: Deactivated for Efficiency
Cylinder shut-off is made possible by an intricate engine management system that incorporates 16 hydraulically compensating actuators and a sophisticated oil supply system within the cylinder head. These actuators, integrated into the cylinder head, maintain the intake and exhaust valves of cylinders two, three, five, and eight in a closed position when cylinder shut-off is engaged. Simultaneously, the fuel supply and ignition to these cylinders are deactivated. This not only minimizes load-change losses from the deactivated cylinders but also enhances the efficiency of the remaining four cylinders by shifting their operating point to a higher load range. The actuators are designed to be compact and lightweight, ensuring precise valve train operation and enabling engine speeds up to 7,200 rpm.
Crankcase and Cylinder Liners: Advanced Material Engineering
The crankcase of the new AMG 5.5-liter V8 engine in the 2012 AMG Mercedes-Benz SLK55 AMG is constructed from diecast all-aluminum. This lightweight construction contributes to the engine’s remarkably low dry weight of just 412 lbs. The bearing covers for the main crankshaft bearings are made of grey cast iron and are bolted to the crankcase both vertically and laterally, enhancing structural rigidity.
To minimize internal friction and reduce wear, the piston rings are coated with carbon. Cast-in Silitec cylinder liners further reduce friction for the eight pistons. A unique “Spectacle” honing process further optimizes friction reduction and fuel consumption. In this sophisticated procedure, the cylinder liners undergo mechanical surface treatment after being bolted in place. A jig, resembling spectacles, is bolted to the crankcase to simulate the distortion that occurs when the cylinder head is installed. The cylinder liners are then honed in this distorted state, ensuring that any static distortion caused by tightening the cylinder head bolts is completely eliminated, leading to improved piston movement and reduced friction.
Further efficiency-enhancing measures integrated into the engine design include:
- Weight-optimized cast aluminum pistons with a special piston skirt coating.
- Dedicated ventilation holes within the crankcase.
- An oil pump featuring an electrically controlled pressure stage.
- A separate, controllable, low-friction vane cell oil pump specifically for cylinder shut-off.
- Engine cooling employing a highly efficient cross-flow principle.
- Electronically controlled, fully variable, and demand-related fuel pressure regulation between 1,450 and 2,900 psi.
The forged crankshaft, crafted from high-grade 38MnS6BY steel alloy, rotates within five main bearings. It features eight counterweights and is optimized for torsional rigidity, inertia, low rotating masses, and extended operational lifespan. A two-mass viscous damper, mounted at the front, effectively mitigates vibrations. Each connecting rod journal on the crankshaft accommodates two forged, cracked connecting rods.
Four-Valve Technology and Variable Camshaft Adjustment
Optimal combustion chamber charging is achieved through large intake and exhaust valves, with four valves per cylinder. The exhaust valves, subjected to significant thermal stress, are hollow and sodium-cooled. Four overhead camshafts actuate the 32 valves via low-maintenance, low-friction cam followers. Infinitely variable camshaft adjustment, within a 40-degree range on both the intake and exhaust sides, adapts to engine load and speed, contributing to high output and torque figures while ensuring consistent idling at low speeds. Valve overlap is variably adjusted based on engine speed to optimize the air-fuel mixture delivery to the combustion chambers and facilitate efficient exhaust gas removal. Hydraulic pivoting actuators, electromagnetically activated and controlled by the engine control unit, manage the variable camshaft adjustment. The camshafts are driven by three high-performance silent chains, which offer notable noise reduction compared to cylinder roller chains.
Controlled Efficiency Stop/Start Function: Standard Feature
The Controlled Efficiency stop/start function, standard on the 2012 AMG Mercedes-Benz SLK55 AMG, further enhances fuel economy. Active in the “C” transmission mode, this system automatically shuts off the V8 engine when the vehicle comes to a stop, such as at traffic lights. Upon releasing the brake pedal or depressing the accelerator, the engine restarts instantaneously, enabling prompt acceleration. Intelligent technology ensures a comfortable and immediate restart: a crankshaft sensor detects the direction of rotation and registers the resting position of all eight pistons. For an automatic engine start, the cylinder with the most favorable piston position receives a fuel injection into its combustion chamber. Precise piezo-electric injectors facilitate exceptionally rapid starts. The M152 engine always restarts in eight-cylinder operation.
An “ECO” symbol, displayed within the AMG main menu, indicates that the Controlled Efficiency stop/start function is active. When cylinder shut-off is also active, the symbol changes to “ECO4”, while “ECO8” signifies eight-cylinder operation. In the more performance-oriented “S” (Sport) and “M” (Manual) driving modes, the stop/start function is automatically deactivated. Drivers can also manually deactivate the function while in “C” mode if desired.
Alternator Management: Further Fuel Savings
An alternator management system further contributes to fuel efficiency. During engine overrun or braking, kinetic energy is harnessed to charge the battery instead of being dissipated as heat. In other operating modes, a combination of onboard network and alternator management maintains the electrical system at a low voltage, reducing parasitic losses and improving overall efficiency.
AMG Sports Exhaust System: Sound Engineering
The 2012 AMG Mercedes-Benz SLK55 AMG debuts a new AMG sports exhaust system featuring an exhaust flap on each side. This innovative technology balances the desire for an emotive exhaust note during spirited driving with the need for a more subdued engine sound during partial load operation. The sound design prioritizes a harmonious blend of perceptible performance and the long-distance cruising comfort synonymous with Mercedes-Benz vehicles.
Each rear silencer incorporates a flap that is variably activated based on driver input and engine speed. At low loads and engine speeds below 2,000 rpm, the flaps remain closed. This forces exhaust gases to travel a longer path through an additional damping element, resulting in a pleasantly subdued engine sound and effective suppression of disruptive frequencies – producing a mellow tone, particularly during four-cylinder operation with cylinder shut-off engaged.
Under acceleration, the flaps progressively open, starting at 15 degrees, then 30, and up to 50 degrees, allowing a portion of the exhaust gases to take a shorter route while the remainder follows the longer, acoustically dampened path, creating a sonorous engine note. Under full load at higher engine speeds in eight-cylinder mode, both flaps fully open, allowing occupants to fully appreciate the muscular and distinctive sound characteristic of an AMG V8 engine, emphasizing the performance capabilities of the 415 hp naturally aspirated powerhouse.
The two-pipe AMG sports exhaust system, featuring two chromed twin tailpipes, has a pipe diameter of 2.56 inches from the manifolds to the pre-silencer, reducing to 2.36 inches from the pre-silencer to the rear silencers.
Emissions Technology: Clean Performance
The exhaust system of the new, naturally aspirated AMG 5.5-liter V8 engine in the 2012 AMG Mercedes-Benz SLK55 AMG is engineered to meet stringent emissions standards, including Euro-5 and US market requirements (LEV-III, On-Board Diagnosis II), while maintaining a characteristic engine sound.
Air gap-insulated manifolds ensure rapid catalytic converter response. For efficiency and space optimization, a tandem catalytic converter housing is used on each side of the vehicle, positioned near the firewall. Each housing contains two thin-walled ceramic substrates. This configuration eliminates the need for previous underbody catalytic converters. The two ceramic substrates differ to ensure rapid and effective emissions control: the front substrate is coated with palladium, while the rear features a bimetal coating of palladium and rhodium. Lambda sensors are positioned upstream and downstream of each catalytic converter housing to monitor and optimize emissions control.
AMG SPEEDSHIFT PLUS 7G-TRONIC: Versatile Power Delivery
Power is transmitted to the rear wheels through the AMG SPEEDSHIFT PLUS 7G-TRONIC automatic transmission, offering three distinct transmission modes: “Controlled Efficiency” (C), Sport (S), and Manual (M). Automatic rev-matching during downshifts and brief, precisely timed interruptions of ignition and injection during upshifts under full load shorten shift times and enhance the driving experience. A double turbine torsional damper with centrifugal pendulum adapts to engine speed, minimizing vibrations during four-cylinder operation and improving overall comfort.
Chassis and Dynamics: Expressive Driving and Comfortable Cruising
The AMG sports suspension, incorporating Torque Vectoring Brakes and AMG Direct-Steer system, delivers both impressive lateral dynamics and agile handling. Whether seeking aggressive driving or comfortable cruising, the 2012 AMG Mercedes-Benz SLK55 AMG adeptly accommodates both. Independent suspension struts with firmer spring and damper tuning, torque strut bearings on the front axle with increased rigidity, stiffer stabilizers at all four corners, and enhanced negative camber on the rear axle contribute to high cornering speeds and reduced body roll during rapid transitions.
In challenging cornering situations, Torque Vectoring Brakes apply selective braking to the inside rear wheel, generating a controlled rotational movement around the vehicle’s vertical axis. This precisely steers the SLK55 AMG into the turn, maintaining control and performance. Complementing this, the AMG Direct-Steer system enhances handling and agility compared to standard steering, while reducing steering effort during parking maneuvers. A new power steering pump further improves fuel efficiency by consuming energy only when steering input is applied. The AMG Direct-Steer system also features a parameter function specifically tuned to the AMG sports suspension, resulting in optimal responsiveness, road feel, and sharp handling in all driving conditions.
The AMG-exclusive 3-stage ESP® system offers driver-selectable control modes: “ESP ON,” “SPORT Handling Mode,” and “ESP OFF,” accessible via a button on the center console. The AMG high-performance braking system features internally ventilated and perforated brake discs on all wheels, measuring 14.2 inches x 1.4 inches at the front and 13 inches x 0.9 inches at the rear, ensuring exceptional responsiveness, short stopping distances, and excellent fade resistance.
Optional AMG Handling Package: Enhanced Dynamics
For drivers seeking even greater driving dynamics, the optional AMG Handling Package further elevates the 2012 AMG Mercedes-Benz SLK55 AMG’s sportiness. This package includes an AMG Performance suspension with firmer tuning, an AMG rear axle differential lock, two-piece front brake discs, and an AMG Performance steering wheel trimmed in premium leather with Alcantara® inserts in the grip areas.
Design and Styling: Unmistakably AMG
The 2012 AMG Mercedes-Benz SLK55 AMG’s design is characterized by classic roadster proportions infused with distinctive AMG styling cues and subtle inspiration from the SLS AMG. The AMG designers have enhanced the inherently appealing form of the long hood, rearward-positioned greenhouse, and crisp rear section with signature AMG styling elements at the front, sides, and rear. The new AMG front apron features large air inlets and AMG-specific LED daytime running lights. The wide radiator grille, reminiscent of the SLS AMG, prominently displays a large, centrally-positioned Mercedes star. On the SLK55 AMG, the front apron slats and lower cross strut are finished in high-gloss black. Darkened clear-lens headlamps and darkened bicolor tail lamps are standard, exclusive to this top-tier V8 model. Bi-Xenon headlights with Active Curve Illumination are available as an option.
The bold front design of the 2012 SLK55 AMG, featuring large air intakes and the prominent Mercedes star grille, emphasizes its AMG performance lineage.
The vent grilles with chrome-plated fins on the front fenders echo the SLS AMG and evoke the iconic Mercedes-Benz 300 SL Roadster from the 1950s. “V8 AMG” lettering beneath the grilles proudly distinguishes the top-of-the-line eight-cylinder model. AMG-specific side sill panels seamlessly connect the front apron design to the new rear apron. The uniquely shaped rear apron incorporates a black diffuser insert with three fins and the dual chrome-plated twin tailpipes of the AMG sports exhaust system, providing a distinctive rear view. The trunk lid spoiler lip, painted in body color, reduces rear axle lift, enhancing high-speed stability.
Interior Design: SLS AMG Inspired
The interior of the 2012 AMG Mercedes-Benz SLK55 AMG is functional, stylish, and crafted with high-quality materials, drawing inspiration from the SLS AMG Roadster. Jet engine-style air vents and a brushed aluminum center console evoke the super sports car. An AMG-specific analog clock, designed by IWC, is centrally positioned on the dashboard. The AMG Performance steering wheel, with a flattened top and bottom, features metal trim, aluminum shift paddles, and perforated leather grip areas. The clearly arranged AMG instrument cluster, positioned for optimal driver visibility, includes four circular instruments, distinctive dials, and the AMG main menu. The transmission mode selector buttons (C, S, M) are conveniently located on the center console.
AMG sports seats offer enhanced lateral support and are upholstered in premium leather with AMG badges embossed in the backrests, complemented by the standard AIRSCARF neck-level heating system.
MAGIC SKY CONTROL: Panoramic Innovation
The standard retractable hardtop transforms the roadster into a coupe in under 20 seconds. Alternatively, a tinted polycarbonate panorama roof panel is available. A groundbreaking option is the panorama roof with MAGIC SKY CONTROL. This innovative glass roof can switch between light and dark at the touch of a button. In its transparent state, it provides an open-air experience even in colder weather. In its darkened state, it offers shade and reduces interior heat buildup from intense sunlight, providing climate comfort at the touch of a button.
The frames of all three roof variants are constructed from magnesium, making each roof approximately 13 lbs lighter than the previous model, lowering the car’s center of gravity and enhancing agility. A comfortable alternative to the standard wind-stop is the new AIRGUIDE pivoting wind-stop, featuring pivoting transparent plastic wings attached to the back of the rollover bars, eliminating the need for manual installation or removal.
Safety and Assistance Systems: Exceptional Standards
The 2012 AMG Mercedes-Benz SLK55 AMG sets new benchmarks for safety, incorporating a suite of advanced assistance systems. Standard safety features include a fiber-reinforced roll-over bar, dual-stage driver and front passenger airbags, headbags, thorax airbags, knee airbags, seat belt tensioners with belt force limiters, NECK-PRO crash-active head restraints, three-stage ESP®, and ATTENTION ASSIST drowsiness detection.
Optional assistance systems include:
- DISTRONIC PLUS: Adaptive cruise control that automatically maintains a set distance from the vehicle ahead, capable of bringing the SLK55 AMG to a complete stop and resuming acceleration.
- PRE-SAFE® Brake: Detects imminent rear-end collisions and prepares for autonomous braking, active between 19 and 124 mph when vehicles are detected ahead.
SLK AMG Heritage: Three Generations of Performance
The 2012 AMG Mercedes-Benz SLK55 AMG represents the third generation of high-performance roadsters from AMG. The lineage began in 2001 with the SLK32 AMG, powered by a supercharged AMG V6 engine producing 349 hp and 332 lb-ft of torque, then the most powerful in its class. In late 2004, the SLK55 AMG debuted with an AMG 5.5-liter V8 engine, generating 355 hp and 376 lb-ft of torque, further cementing its segment leadership. Mercedes-AMG has remained committed to the philosophy of offering a large-displacement eight-cylinder engine in this class, a tradition continued and elevated with the 2012 SLK55 AMG. The 2012 SLK55 AMG marked a new chapter in this legacy when it launched in the U.S. market in early 2012, solidifying its position as a benchmark in the world of high-performance roadsters.
