The 2012 Mercedes-Benz SLK55 AMG stands as a testament to the enduring appeal of high-performance roadsters, blending raw power with sophisticated technology and luxurious comfort. As the most potent SLK variant of its time, the 2012 model year marked a significant leap forward, introducing a new AMG 5.5-liter V8 engine that redefined expectations for fuel efficiency and exhilarating performance in its class. This article delves into the specifics of the 2012 SLK55 AMG, exploring its engine, design, driving dynamics, and innovative features that cemented its position as a leader in the compact, high-performance roadster segment.
The heart of the 2012 SLK55 AMG is its groundbreaking AMG 5.5-liter V8 engine, a masterpiece of engineering that delivers a formidable 415 horsepower and 398 lb-ft of torque. This powerplant is not just about brute strength; it incorporates advanced technologies like cylinder shut-off, ensuring a harmonious balance between breathtaking performance and optimized fuel consumption. This innovative approach allowed the SLK55 AMG to outperform its competitors while also setting new benchmarks for efficiency in the V8 engine category. The promise of high-performance driving is further realized through the AMG sports suspension, featuring a Direct-Steer system, Torque Vectoring Brakes, and 3-stage ESP®, all working in concert with the AMG high-performance braking system to provide an unmatched driving experience.
Visually, the 2012 SLK55 AMG makes a striking first impression, embodying the athletic elegance synonymous with the AMG brand. Distinctive AMG light-alloy wheels and exclusive AMG body styling, complete with an AMG spoiler lip, immediately set it apart. The rear is accentuated by two chrome-plated twin tailpipes, adding a touch of aggressive sophistication to the classic roadster silhouette. This expressive design is not merely aesthetic; it’s a clear statement of the vehicle’s high-performance pedigree and unmistakable character.
The 2012 Mercedes-Benz SLK55 AMG perfectly embodies AMG’s “Driving Performance” philosophy. It is designed to offer an unparalleled combination of dynamic driving capabilities, superior sportiness, and cutting-edge technology, all while maintaining a focus on fuel efficiency. In the realm of compact high-performance roadsters, the SLK55 AMG stands alone, delivering tangible driving dynamics that are simply unmatched. Performance figures speak volumes: the SLK55 AMG accelerates from 0 to 60 mph in just 4.5 seconds, reaching an electronically limited top speed of 155 mph.
Performance Metrics: 2012 SLK55 AMG at a Glance
To truly understand the capabilities of the 2012 SLK55 AMG, examining its key performance figures is crucial. The following table provides a detailed overview of the specifications that define this high-performance roadster:
| Feature | Specification |
|---|---|
| Displacement | 5,461 cc |
| Bore x Stroke | 3.86 in x 3.56 in |
| Compression Ratio | 12.6 : 1 |
| Peak Output | 415 hp @ 6,800 rpm |
| Maximum Torque | 398 lb-ft @ 4,500 rpm |
| Engine Weight (dry) | 412 lbs |
| 0-60 mph Acceleration | 4.5 seconds |
| Top Speed | 155 mph (electronically limited) |
These figures underscore the engineering prowess behind the 2012 SLK55 AMG. The naturally aspirated 5.5-liter V8 engine is meticulously designed to deliver not only raw power but also a refined driving experience. The engine’s ability to achieve high output while adhering to stringent fuel efficiency standards is a testament to AMG’s commitment to “Performance 2015,” a strategy focused on reducing fuel consumption and emissions across their model range.
The Innovative M152 Engine: Heart of the 2012 SLK55 AMG
The engine powering the 2012 SLK55 AMG, known as the M152, is a marvel of modern automotive engineering. It shares a close relationship with the M157 5.5-liter V8 biturbo engine, which debuted in 2010 and powered other high-performance AMG models like the E63 AMG and CLS63 AMG. The M152 retains numerous key design features from the M157, including displacement, bore/stroke dimensions, cylinder spacing, ECO stop/start system, and direct gasoline injection technology.
However, the M152 distinguishes itself through several key modifications tailored for the SLK55 AMG’s naturally aspirated configuration. These include:
- New Intake Air Ducting: Optimized for naturally aspirated performance.
- New Cylinder Heads: Redesigned to enhance airflow and combustion efficiency.
- Modified Valve Drive: Fine-tuned for the specific engine characteristics.
- Adapted Oil Supply System: Engineered to ensure optimal lubrication under various driving conditions.
- Optimized Crankcase: Refined for weight reduction and structural integrity.
This exclusive combination of advanced technologies sets the M152 engine apart. Its high-tech features are unparalleled in the automotive world, including:
- Direct Injection at 2,900 psi: Ensures precise fuel delivery and efficient combustion.
- Spray-Guided Combustion: Optimizes fuel-air mixture for enhanced performance and reduced emissions.
- Piezo Injectors: Enable ultra-precise fuel metering and rapid response.
- Map-Controlled Cylinder Shut-off: Enhances fuel efficiency by deactivating cylinders under partial load.
- All-Aluminum Crankcase with “Spectacle” Honing: Reduces weight and friction for improved efficiency.
- Four-Valve Technology with Continuous Camshaft Adjustment: Optimizes engine performance across the rev range.
- High Compression Ratio of 12.6 : 1: Increases thermodynamic efficiency and power output.
- Stop/Start System: Further improves fuel economy in urban driving conditions.
- Generator Management: Recovers energy during braking and deceleration.
These technologies collectively contribute to the M152 engine’s exceptional thermodynamic efficiency, which is paramount for achieving both high fuel economy and low exhaust emissions. The use of a large-displacement, naturally aspirated eight-cylinder engine with cylinder shut-off effectively addresses the traditional trade-off between power and fuel consumption.
AMG Cylinder Management: Efficiency through Innovation
A standout feature of the 2012 SLK55 AMG is the AMG Cylinder Management system. This technology, developed entirely by Mercedes-AMG, significantly boosts fuel efficiency by selectively shutting off cylinders under partial load. Specifically, cylinders two, three, five, and eight are deactivated when the system is engaged. This concept is inspired by Formula 1 technology, where cylinder shut-off is used in 750-hp V8 engines for efficiency during slow cornering, safety car periods, or pit stops.
The cylinder shut-off system operates within an engine speed range of 800 to 3,600 rpm when the driver selects “C” (Controlled Efficiency) transmission mode. The AMG main menu in the instrument cluster provides real-time feedback, informing the driver whether cylinder shut-off is active and if the engine is running in four or eight-cylinder mode. Even in four-cylinder mode, the engine still delivers a substantial 170 lb-ft of torque, providing ample power for everyday driving. The transition between four and eight-cylinder operation is seamless and imperceptible, ensuring no compromise in occupant comfort. At 3,600 rpm, the activation process takes a mere 30 milliseconds.
The cylinder shut-off is achieved through an intelligent engine management system, incorporating 16 hydraulically compensating actuators and a sophisticated oil supply system within the cylinder head. These actuators, integrated into the cylinder head, keep the intake and exhaust valves of the deactivated cylinders (two, three, five, and eight) closed. Simultaneously, fuel supply and ignition to these cylinders are deactivated. This reduces load-change losses and enhances the efficiency of the remaining four cylinders by shifting their operating point to a higher load range. The compact and lightweight design of the actuators allows for taut valve train operation and engine speeds up to 7,200 rpm.
Advanced Engine Components and Efficiency Measures
The 2012 SLK55 AMG engine incorporates numerous advanced components and design features aimed at maximizing efficiency and performance. The crankcase is constructed from diecast all-aluminum, contributing to a low dry engine weight of just 412 lbs, a result of meticulous lightweight construction. Grey cast iron bearing covers for the main crankshaft bearings are bolted to the crankcase and sides, enhancing rigidity.
Further efficiency-enhancing measures include:
- Carbon-Coated Piston Rings: Minimize internal friction and reduce wear.
- Cast-in Silitec Cylinder Liners: Ensure low friction for the pistons.
- “Spectacle” Honing: A unique process that mechanically treats cylinder liners after they are bolted in place, eliminating static distortion caused by cylinder head bolt tightening and further reducing friction.
- Weight-Optimized Cast Aluminum Pistons: Feature special piston skirt coatings.
- Special Ventilation Holes in the Crankcase: Reduce oil churning losses.
- Electrically Controlled Oil Pump: Features pressure staging for demand-based lubrication.
- Separate Oil Pump for Cylinder Shut-off: A controllable, low-friction vane cell pump.
- Efficient Cross-Flow Engine Cooling: Optimizes heat dissipation.
- Electronically Controlled Fuel Pressure: Fully variable and demand-related between 1,450 and 2,900 psi.
The forged crankshaft, made from high-grade 38MnS6BY steel alloy, rotates on five main bearings and is designed for torsional rigidity, low inertia, and durability. A two-mass viscous damper at the front effectively minimizes vibrations. Forged, cracked connecting rods are used on each connecting rod journal of the crankshaft.
Four-Valve Technology and Variable Camshaft Adjustment
Optimal combustion chamber charging in the 2012 SLK55 AMG is achieved through large intake and exhaust valves, with four valves per cylinder. The exhaust valves, subjected to high thermal stress, are hollow and sodium-cooled. Four overhead camshafts operate the 32 valves via low-maintenance, low-friction cam followers.
Infinitely variable camshaft adjustment, within a 40-degree range on both intake and exhaust sides, adapts to engine load and speed. This results in high power and torque output, as well as stable idling at low speeds. Valve overlap is varied based on engine speed to optimize the fuel/air supply and 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 low-noise, high-performance silent chains.
Controlled Efficiency Stop/Start Function and Alternator Management
The Controlled Efficiency stop/start function is standard on the 2012 SLK55 AMG, further enhancing fuel economy. Active in “C” mode, it automatically shuts off the V8 engine when the vehicle comes to a stop, such as at traffic lights. The engine restarts instantly upon release of the brake pedal or depression of the accelerator, ensuring quick and comfortable restarts. A crankshaft sensor detects rotation direction and piston positions, allowing for immediate fuel injection into the cylinder with the most favorable piston position for rapid starting. The M152 engine always starts in eight-cylinder mode.
The instrument cluster displays an “ECO” symbol when the stop/start function is active. “ECO4” indicates four-cylinder operation due to cylinder shut-off, while “ECO8” signifies eight-cylinder operation. In “S” (Sport) and “M” (Manual) driving modes, the stop/start function is deactivated. Drivers can also manually deactivate it in “C” mode.
Alternator management further contributes to fuel efficiency by using kinetic energy during overrun or braking to charge the battery, instead of wasting it as heat. In other operating modes, the system maintains a low voltage in the electrical system.
AMG Sports Exhaust System: Sound and Efficiency
The 2012 SLK55 AMG debuts a new AMG sports exhaust system featuring an exhaust flap on each side. This technology balances the desire for an emotive exhaust note during spirited driving with a more subdued sound during partial load conditions. The sound design prioritizes a synthesis of performance audibility and long-distance comfort.
Each rear silencer incorporates a flap that is variably activated based on driver input and engine speed. Below 2,000 rpm and under low loads, these flaps remain closed, directing exhaust gases through a longer path and an additional damping element. This results in a pleasantly subdued engine sound, effectively suppressing disruptive frequencies, particularly noticeable in four-cylinder operation.
Upon acceleration, the flaps progressively open (15, 30, up to 50 degrees), creating a more direct exhaust path while maintaining some acoustic damping, producing a sonorous engine note. Under full load and at higher engine speeds in eight-cylinder mode, both flaps fully open, unleashing the distinct, muscular sound characteristic of an AMG V8, emphasizing the 415 hp engine’s performance potential.
The two-pipe AMG sports exhaust system features chrome-plated twin tailpipes and varying pipe diameters to optimize sound and performance.
Emission Control Technology
The 2012 SLK55 AMG is engineered to meet stringent emissions standards, including Euro-5 and US market requirements (LEV-III, On-Board Diagnosis II). Air gap-insulated manifolds ensure rapid catalytic converter response. The exhaust system employs tandem catalytic converter housings on each side, positioned close to the firewall. Each housing contains two thin-walled ceramic substrates, eliminating the need for underbody catalytic converters. The substrates are specifically coated for efficient emissions control: the front with palladium, and the rear with a bimetal coating of palladium and rhodium. Lambda sensors are positioned before and between the substrates for precise emissions monitoring.
AMG SPEEDSHIFT PLUS 7G-TRONIC Transmission
Power in the 2012 SLK55 AMG is delivered to the rear wheels via the AMG SPEEDSHIFT PLUS 7G-TRONIC automatic transmission. This transmission offers three modes: “Controlled Efficiency” (C), Sport (S), and Manual (M). Automatic rev-matching during downshifts and brief ignition/injection interruption during upshifts in Sport and Manual modes reduce shift times and enhance the driving experience. A double turbine torsional damper with centrifugal pendulum adapts to engine speed, minimizing vibrations, especially during four-cylinder operation, and improving overall comfort.
Driving Dynamics: Suspension, Steering, and Braking
The AMG sports suspension, combined with Torque Vectoring Brakes and the AMG Direct-Steer system, provides the 2012 SLK55 AMG with impressive lateral dynamics and agile handling. The suspension features independent struts with stiffer spring/damper tuning, torque strut bearings on the front axle, stiffer stabilizers, and increased negative camber on the rear axle, resulting in high cornering speeds and reduced body roll.
Torque Vectoring Brakes enhance cornering by applying selective braking to the inside rear wheel, inducing a rotational movement that helps steer the car into turns more precisely. The AMG Direct-Steer system improves handling and agility while reducing parking effort. A new power steering pump reduces fuel consumption by operating only when steering input is detected. The AMG Direct-Steer system is specifically tuned to complement the AMG sports suspension, providing optimal response and road feel in all driving situations.
The AMG-exclusive 3-stage ESP® system offers “ESP ON,” “SPORT Handling Mode,” and “ESP OFF” settings, allowing drivers to tailor the electronic stability program to their driving style. The AMG high-performance braking system features internally ventilated and perforated brake discs for exceptional responsiveness, short stopping distances, and fade resistance.
Optional AMG Handling Package
For drivers seeking even greater driving dynamics, the optional AMG Handling Package is available. This package includes:
- AMG Performance Suspension: Features a stiffer suspension setup.
- AMG Rear Axle Differential Lock: Enhances traction and cornering performance.
- Two-Piece Brake Discs at the Front: Improve braking performance and heat dissipation.
- AMG Performance Steering Wheel: A three-spoke design in premium leather with Alcantara® inserts for enhanced grip.
Exterior and Interior Design: AMG Signature Touches
The 2012 SLK55 AMG’s design blends classic roadster proportions with distinctive AMG styling cues. The front end features a new AMG front apron with large air inlets and AMG-specific LED daytime running lights. The wide radiator grille, inspired by the SLS AMG, prominently displays a central Mercedes star. High-gloss black finishes on the front apron elements and darkened clear-lens headlamps and bicolor tail lamps further distinguish the V8 model. Bi-Xenon headlights with Active Curve Illumination are optional.
Vent grilles with chrome-plated fins on the front fenders, reminiscent of both the SLS AMG and the classic Mercedes-Benz 300 SL Roadster, add a touch of heritage and exclusivity. “V8 AMG” lettering highlights the top-of-the-range status. AMG-specific side sill panels and a unique rear apron with a black diffuser insert and chrome-plated twin tailpipes complete the exterior enhancements. A body-colored spoiler lip on the trunk lid reduces lift at high speeds.
The interior of the 2012 SLK55 AMG echoes the SLS AMG Roadster, featuring jet engine-style air vents and a brushed aluminum center console. An AMG-specific analog clock with IWC design is positioned centrally on the dashboard. The AMG Performance steering wheel, with a flattened top and bottom, includes metal trim, aluminum shift paddles, and perforated leather grip areas. The AMG instrument cluster features four circular gauges and an AMG main menu. AMG sports seats offer enhanced lateral support, premium leather upholstery with AMG badges, and the standard AIRSCARF neck-level heating system.
Roof Options: MAGIC SKY CONTROL Panorama Roof
The 2012 SLK55 AMG features a standard retractable hardtop that opens and closes in under 20 seconds. Optional roof choices include a tinted polycarbonate panorama roof and the innovative panorama roof with MAGIC SKY CONTROL. MAGIC SKY CONTROL allows the glass roof to switch between light and dark at the touch of a button, offering an open-air feel even in cold weather or shading from intense sunlight. Magnesium frames for all roof variants reduce weight and lower the car’s center of gravity. The AIRGUIDE pivoting wind-stop is a comfortable alternative to traditional wind deflectors.
Safety and Assistance Systems
The 2012 SLK55 AMG is equipped with a comprehensive suite of safety and assistance systems, including fiber-reinforced roll-over bars, multi-stage airbags, NECK-PRO head restraints, 3-stage ESP®, and ATTENTION ASSIST.
Optional assistance systems include:
- DISTRONIC PLUS: Adaptive cruise control that maintains a set distance from the vehicle ahead, including stop-and-go functionality.
- PRE-SAFE® Brake: Autonomous emergency braking system that detects imminent rear-end collisions and prepares for braking.
Legacy of the SLK AMG
The 2012 SLK55 AMG represents the third generation of high-performance roadsters from AMG, building upon the legacy of the SLK32 AMG (2001) and the original SLK55 AMG (2004). Each model has pushed the boundaries of performance and technology in the compact roadster segment, with the 2012 SLK55 AMG continuing this tradition with its powerful V8 engine, innovative technologies, and distinctive AMG design. The 2012 Mercedes-Benz SLK55 AMG is a compelling blend of power, luxury, and innovation, solidifying its place as a benchmark in the world of performance roadsters.
