The Mercedes-Benz S 350 BlueEFFICIENCY, produced from 2011 to 2013, was a variant of the W221 S-Class facelift model. Positioned as a mid-range offering within the lineup, it aimed to provide a balance between performance, efficiency, and luxury. This model represented a refinement of the W221 platform, introduced in 2005, with updates focused on improved fuel economy and reduced emissions. The S 350 BlueEFFICIENCY utilized a naturally aspirated 3.5-liter V6 engine paired with the 7G-TRONIC automatic transmission, catering to buyers seeking a comfortable and refined driving experience without the added cost or complexity of the higher-performance S 550 or diesel-powered S 350 CDI models.
Powertrain & Engine Architecture
The heart of the S 350 BlueEFFICIENCY is the M 276.950 engine, a 3.5-liter (3498 cc / 213.46 cu. in.) naturally aspirated V6. This engine is characterized by its all-aluminum construction, contributing to weight reduction and improved thermal management. It features a compression ratio of 12:1 and four valves per cylinder. The engine employs direct fuel injection, a technology that precisely meters fuel directly into the combustion chamber, enhancing efficiency and power output. The M 276 engine family was notable for its adoption of a balance shaft to minimize vibrations inherent in V6 configurations.
The 7G-TRONIC automatic transmission, a seven-speed unit, was standard equipment. This transmission was known for its smooth and responsive shifts, contributing to the overall refinement of the driving experience. It featured a torque converter lock-up clutch that engaged in most driving situations, improving fuel efficiency. The transmission offered selectable driving modes, allowing the driver to tailor the shift points to their preferences or driving conditions. The transmission’s gear ratios were optimized for both comfortable cruising and responsive acceleration.
Engine Specifications
The M 276.950 engine produces 306 horsepower (Hp) at 6500 rpm and 370 Newton-meters (272.9 lb.-ft.) of torque at 3500 rpm. This translates to a power-to-liter ratio of 87.5 Hp/l. The engine’s power delivery is linear and predictable, making it well-suited for everyday driving. The engine oil capacity is 6.5 liters (6.87 US qt / 5.72 UK qt), and the recommended oil specification is detailed in the vehicle’s owner’s manual.
Driving Characteristics
The S 350 BlueEFFICIENCY offered a comfortable and composed driving experience. While not as overtly powerful as the S 550, the 306 hp V6 provided ample power for effortless cruising and confident overtaking. Acceleration from 0 to 100 km/h (0-62 mph) took approximately 6.9 seconds, and 0-60 mph was achieved in around 6.6 seconds. The 7G-TRONIC transmission contributed to smooth and seamless gear changes, minimizing disruptions to the driving experience. The rear-wheel drive configuration provided a balanced feel, although it lacked the all-weather capability of the 4MATIC all-wheel drive system available on other S-Class models.
Compared to the higher-output S 550, the S 350 BlueEFFICIENCY felt less urgent in its acceleration. However, it offered a more relaxed and refined driving experience, particularly at highway speeds. The S 350 CDI diesel variant provided even greater torque and fuel economy, but at the expense of some refinement and the characteristic smoothness of a gasoline engine.
Equipment & Trim Levels
The S 350 BlueEFFICIENCY came standard with a comprehensive array of luxury features. These included leather upholstery, power-adjustable front seats with memory function, dual-zone automatic climate control, a premium audio system, and a navigation system. Standard safety features included ABS, electronic stability control, and a suite of airbags. The interior trim was typically finished in wood or aluminum, offering a sophisticated and elegant ambiance.
Optional extras included a panoramic sunroof, rear seat entertainment system, massaging seats, and a driver assistance package that included features such as adaptive cruise control and lane keeping assist. The S 350 BlueEFFICIENCY could be further customized with a variety of exterior paint colors and wheel designs.
Chassis & Braking
The S 350 BlueEFFICIENCY utilized a fully independent suspension system, featuring multi-link suspension at both the front and rear. This suspension design provided a comfortable ride and precise handling. The car was equipped with disc brakes on all four wheels, providing ample stopping power. ABS (Anti-lock Braking System) was standard, enhancing braking performance and stability. The steering system employed a rack-and-pinion setup, offering precise and responsive steering feel.
The standard tire size was 235/55 R17, mounted on 17-inch alloy wheels. The suspension was tuned to prioritize ride comfort, but it also provided a reasonable level of handling competence. Stabilizer bars were fitted to both the front and rear axles to reduce body roll during cornering.
Market Reception & Comparison
The S 350 BlueEFFICIENCY was generally well-received by automotive critics. It was praised for its comfortable ride, refined interior, and efficient engine. Fuel economy figures were rated at 7.6-7.9 l/100 km (30.9 – 29.8 US mpg, 37.2 – 35.8 UK mpg, 13.2 – 12.7 km/l), making it a relatively economical option within the luxury sedan segment. Compared to the S 550, the S 350 BlueEFFICIENCY offered a better balance between performance and fuel economy. The S 350 CDI diesel variant provided even better fuel economy, but some critics noted that it lacked the smoothness and refinement of the gasoline engine.
Reliability reports generally indicated that the M 276 engine and 7G-TRONIC transmission were relatively reliable, although routine maintenance was essential to ensure long-term durability. Common issues included oil leaks and occasional transmission glitches, but these were typically addressed with regular servicing.
Technical Specifications
| Body Type | Sedan, 4 Doors, 5 Seats |
| Fuel Economy (Combined) | 7.6-7.9 l/100 km (30.9 – 29.8 US mpg, 37.2 – 35.8 UK mpg, 13.2 – 12.7 km/l) |
| CO2 Emissions | 177-184 g/km |
| Emission Standard | Euro 5 |
| Maximum Speed | 250 km/h (155.34 mph) |
| Acceleration 0-100 km/h | 6.9 sec |
| Acceleration 0-60 mph | 6.6 sec |
| Engine Layout | Front, Longitudinal |
| Engine Model/Code | M 276.950 |
| Engine Displacement | 3498 cm3 (213.46 cu. in.) |
| Number of Cylinders | 6 |
| Engine Configuration | V-engine |
| Compression Ratio | 12:1 |
| Fuel Injection System | Direct Injection |
| Engine Oil Capacity | 6.5 l (6.87 US qt | 5.72 UK qt) |
| Kerb Weight | 1835 kg (4045.48 lbs.) |
| Max. Weight | 2505 kg (5522.58 lbs.) |
| Trunk (Boot) Space | 560 l (19.78 cu. ft.) |
| Fuel Tank Capacity | 83 l (21.93 US gal | 18.26 UK gal) |
| Length | 5096 mm (200.63 in.) |
| Width | 1871 mm (73.66 in.) |
| Height | 1479 mm (58.23 in.) |
| Wheelbase | 3035 mm (119.49 in.) |
| Number of Gears & Gearbox Type | 7 gears, automatic transmission G-TRONIC |
Legacy
The S 350 BlueEFFICIENCY, while not the most powerful or prestigious variant of the W221 S-Class, remains a desirable option in the used car market. Its combination of luxury, comfort, and relatively good fuel economy makes it an appealing choice for buyers seeking a high-end sedan without the expense of the flagship models. The M 276 engine has proven to be reasonably durable, and the 7G-TRONIC transmission is generally reliable when properly maintained. As with any used luxury vehicle, prospective buyers should carefully inspect the car’s maintenance history and consider a pre-purchase inspection by a qualified mechanic.
The W221 S-Class, including the S 350 BlueEFFICIENCY, represented a significant step forward in automotive technology and luxury. It established a benchmark for ride comfort, safety, and refinement, and its influence can still be seen in modern Mercedes-Benz vehicles.
