The Mercedes-Benz SLK (R172) SLK 350 V6 (306 Hp) 7G-TRONIC PLUS represents the third generation of Mercedes-Benz’s compact luxury roadster, produced from 2011 to 2015. Known for its blend of sporty performance, sophisticated design, and open-air driving pleasure, the R172 generation aimed to refine the successful formula established by its predecessors. The SLK, an acronym for “Sportlich, Leicht, Kurz” (Sporty, Light, Short), perfectly encapsulated the vehicle’s design philosophy. The SLK 350 V6 variant, in particular, stood out as a compelling choice within the lineup, offering a potent naturally aspirated V6 engine paired with an advanced automatic transmission, delivering a dynamic driving experience synonymous with the Mercedes-Benz brand in the premium roadster segment.
Mercedes-Benz SLK (R172) SLK 350 V6: A Detailed Overview
The R172 SLK built upon the foundations laid by the R107 and R170 generations, continuing Mercedes-Benz’s tradition of producing refined and capable roadsters. This generation introduced a more aggressive styling language, drawing inspiration from the iconic Mercedes-Benz SLS AMG, along with an array of technological advancements designed to enhance comfort, safety, and performance. The SLK was primarily marketed in Europe and North America, appealing to buyers seeking a luxurious and sporty open-top experience.
Engine & Performance
At the heart of the SLK 350 V6 was the M 276.956 engine, a 3.5-liter (3498 cm3) naturally aspirated V6 powerplant. This engine was engineered for smooth, linear power delivery and a characteristic Mercedes-Benz exhaust note. It produced a robust 306 horsepower at 6500 rpm, demonstrating a strong inclination towards higher revs for peak performance. Complementing this, the engine delivered a substantial 272.9 lb.-ft. of torque across a broad and accessible range, from 3500 to 5250 rpm, ensuring brisk acceleration and flexible in-gear performance. The direct injection fuel system, coupled with a DOHC (Double Overhead Camshaft) valvetrain and a high 12:1 compression ratio, optimized combustion efficiency and power output.
Power was seamlessly managed by Mercedes-Benz’s advanced 7G-TRONIC PLUS automatic transmission. This seven-speed gearbox was renowned for its smooth shifts and intelligent programming, adapting to various driving styles while contributing to both performance and fuel efficiency. The drivetrain architecture featured rear-wheel drive, a classic configuration for sports cars that ensured a balanced feel and engaging handling dynamics. Performance figures for the SLK 350 V6 were impressive for its class. It could accelerate from 0 to 60 mph in a swift 5.3 seconds, with 0 to 100 km/h achieved in 5.6 seconds. The top speed was electronically limited to 155 mph (250 km/h), a common practice for German luxury vehicles. Despite its performance capabilities, Mercedes-Benz incorporated efficiency-enhancing technologies like the Start & Stop System, contributing to a combined fuel consumption rating of 33.1 US mpg (7.1 l/100 km) and CO2 emissions of 167 g/km, meeting Euro 5 emission standards. The weight-to-power ratio of 4.8 kg/Hp (208.9 Hp/tonne) further underscored its athletic credentials.
Design & Features
The exterior design of the Mercedes-Benz SLK (R172) marked a significant departure from its predecessor, adopting a more masculine and assertive aesthetic. Its front fascia, with a prominent grille and swept-back headlights, paid homage to the Mercedes-Benz SLS AMG supercar, giving the compact roadster a more upscale and aggressive presence. The car maintained its characteristic roadster body type, a two-door, two-seat configuration, featuring Mercedes-Benz’s signature retractable hardtop. This Vario-roof system allowed owners to transform the car from a secure coupe to an open-air roadster in mere seconds, offering the best of both worlds.
Measuring 162.76 inches in length, 71.26 inches in width (78.98 inches including mirrors), and 51.22 inches in height, the R172 had a compact footprint, making it agile and easy to maneuver. Its wheelbase stretched 95.67 inches, contributing to stability. The drag coefficient of 0.32 Cd was commendable for a roadster, aiding both fuel efficiency and high-speed stability. The kerb weight of 3229.77 lbs (1465 kg) highlighted its relatively light construction, important for a sporty vehicle.
Inside, the SLK 350 V6 offered a cabin that exuded Mercedes-Benz’s hallmark of luxury and ergonomic design. High-quality materials, precise fit and finish, and a driver-focused cockpit created an inviting environment. Key features for this modern car included advanced safety systems like ABS (Anti-lock Braking System), and implicitly, other electronic stability controls that were standard for Mercedes-Benz at the time. The hydraulic power steering system provided direct feedback, enhancing the driving experience. The suspension setup, with an independent McPherson-type front and a multi-link rear, was tuned to offer a balance of sporty handling and comfortable ride quality. The car rode on a staggered wheel and tire setup: 225/45 R17 tires on 7.5J x 17 rims at the front and wider 245/40 R17 tires on 8.5J x 17 rims at the rear, optimizing grip and visual appeal. Trunk space, a common consideration for roadsters with retractable hardtops, ranged from 7.95 cu. ft. (225 liters) with the roof down to 11.83 cu. ft. (335 liters) with the roof up, offering reasonable practicality for weekend getaways. The fuel tank capacity of 15.85 US gallons (60 liters) provided a decent cruising range.
Technical Specifications
| Specification | Value |
| Brand | Mercedes-Benz |
| Model | SLK |
| Generation | SLK (R172) |
| Type (Engine) | SLK 350 V6 (306 Hp) 7G-TRONIC PLUS |
| Production Start | 2011 |
| Production End | 2015 |
| Powertrain Architecture | Internal Combustion Engine |
| Body type | Roadster |
| Seats | 2 |
| Doors | 2 |
| Performance Specs | |
| Fuel Consumption (Urban) | 23.8 US mpg (9.9 l/100 km) |
| Fuel Consumption (Extra Urban) | 42.8 US mpg (5.5 l/100 km) |
| Fuel Consumption (Combined) | 33.1 US mpg (7.1 l/100 km) |
| CO2 Emissions | 167 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 60 mph | 5.3 sec |
| Acceleration 0 – 100 km/h | 5.6 sec |
| Maximum Speed | 155.34 mph (250 km/h, Electronically limited) |
| Emission Standard | Euro 5 |
| Weight-to-Power Ratio | 10.58 lbs/Hp (4.8 kg/Hp) |
| Weight-to-Torque Ratio | 8.82 lbs/lb.-ft. (4 kg/Nm) |
| Engine Specs | |
| Power | 306 Hp @ 6500 rpm |
| Power per liter | 87.5 Hp/l |
| Torque | 272.9 lb.-ft. @ 3500-5250 rpm (370 Nm) |
| Engine Layout | Front, Longitudinal |
| Engine Model/Code | M 276.956 |
| Engine Displacement | 213.46 cu. in. (3498 cm3) |
| Number of Cylinders | 6 |
| Engine Configuration | V-engine |
| Cylinder Bore | 3.66 in. (92.9 mm) |
| Piston Stroke | 3.39 in. (86 mm) |
| Compression Ratio | 12:1 |
| Number of Valves per Cylinder | 4 |
| Fuel Injection System | Direct injection |
| Engine Aspiration | Naturally aspirated engine |
| Valvetrain | DOHC |
| Engine Oil Capacity | 6.87 US qt (6.5 l) |
| Coolant Capacity | 10.99 US qt (10.4 l) |
| Engine Systems | Start & Stop System |
| Space, Volume and Weights | |
| Kerb Weight | 3229.77 lbs (1465 kg) |
| Max. Weight | 4089.57 lbs (1855 kg) |
| Max Load | 859.8 lbs (390 kg) |
| Trunk (boot) Space – Minimum | 7.95 cu. ft. (225 l) |
| Trunk (boot) Space – Maximum | 11.83 cu. ft. (335 l) |
| Fuel Tank Capacity | 15.85 US gal (60 l) |
| Dimensions | |
| Length | 162.76 in. (4134 mm) |
| Width | 71.26 in. (1810 mm) |
| Width including mirrors | 78.98 in. (2006 mm) |
| Height | 51.22 in. (1301 mm) |
| Wheelbase | 95.67 in. (2430 mm) |
| Front Track | 61.38 in. (1559 mm) |
| Rear (Back) Track | 61.61 in. (1565 mm) |
| Front Overhang | 34.25 in. (870 mm) |
| Rear Overhang | 32.83 in. (834 mm) |
| Drag Coefficient (Cd) | 0.32 |
| Minimum Turning Circle | 34.51 ft. (10.52 m) |
| Drivetrain, Brakes and Suspension Specs | |
| Drivetrain Architecture | Internal Combustion Engine drives the rear wheels |
| Drive Wheel | Rear Wheel Drive |
| Number of Gears & Gearbox Type | 7 gears, automatic transmission G-TRONIC PLUS |
| Front Suspension | Independent, McPherson type with coil spring and anti-roll bar |
| Rear Suspension | Independent multi-link spring suspension with stabilizer |
| Front Brakes | Ventilated discs |
| Rear Brakes | Disc |
| Assisting Systems | ABS (Anti-lock Braking System) |
| Steering Type | Steering rack and pinion |
| Power Steering | Hydraulic Steering |
| Front Wheel Tires Size | 225/45 R17 |
| Rear Wheel Tires Size | 245/40 R17 |
| Front Wheel Rims Size | 7.5J x 17 |
| Rear Wheel Rims Size | 8.5J x 17 |
The Mercedes-Benz SLK (R172) SLK 350 V6 cemented its place in the market as a highly desirable premium compact roadster. It carried on the legacy of its predecessors, offering a compelling blend of luxury, performance, and the unique appeal of a retractable hardtop. The R172 generation was particularly lauded for its more masculine and sophisticated styling, which resonated well with consumers seeking a sportier aesthetic than previous SLK models.
In its competitive landscape, the SLK 350 V6 faced formidable rivals such as the BMW Z4 (E89 generation), the Audi TT Roadster, and the Porsche Boxster (981 generation). While the Porsche Boxster often held the edge in pure driving dynamics and raw sportiness, the SLK 350 V6 countered with a distinct emphasis on luxurious comfort, refinement, and a broader appeal as a stylish cruiser that could also deliver exhilarating performance when called upon. Its retractable hardtop offered advantages in terms of noise insulation and security compared to soft-top rivals, a significant selling point for many buyers.
Ultimately, the Mercedes-Benz SLK (R172) SLK 350 V6 (306 Hp) 7G-TRONIC PLUS left a lasting impression as a well-rounded and appealing luxury roadster. It successfully combined traditional Mercedes-Benz elegance and comfort with modern technology and spirited performance, making it a significant model in the brand’s history and a cherished choice for enthusiasts of open-top motoring.
