2009-2010 Mercedes-Benz S-class (W221 facelift ) S 350 CDI BlueEFFICIENCY (235 Hp) 4MATIC G-TRONIC

The Mercedes-Benz S 350 CDI BlueEFFICIENCY 4MATIC, produced from 2009 to 2010, was a significant variant within the W221 S-Class facelift range. Representing a blend of luxury, performance, and fuel efficiency, this model occupied a middle ground in the S-Class lineup, positioned between the entry-level S 300 CDI and the more powerful S 500 models. It catered to buyers seeking a sophisticated full-size sedan with a diesel engine, all-wheel drive capability, and advanced technology. The W221 generation S-Class, launched in 2005, represented a substantial leap forward in Mercedes-Benz technology and refinement, and the 2009 facelift further enhanced its appeal with updated styling, improved efficiency, and advanced driver-assistance systems.

Powertrain & Engine Architecture

The heart of the S 350 CDI BlueEFFICIENCY 4MATIC is the OM 642.930 3.0-liter V6 diesel engine. This engine is a longitudinally mounted, turbocharged common rail diesel, producing 235 horsepower at 3600 rpm and a substantial 540 Nm (398.28 lb-ft) of torque between 1600 and 2400 rpm. The high torque output, characteristic of modern diesel engines, provides strong acceleration and effortless cruising. The engine features a compression ratio of 17.7:1 and utilizes four valves per cylinder. The turbocharger, coupled with an intercooler, enhances power and efficiency by increasing air density entering the engine. The “BlueEFFICIENCY” designation signifies Mercedes-Benz’s efforts to improve fuel economy and reduce emissions through various technologies, including optimized engine management and reduced internal friction.

Paired with the engine is the 7G-TRONIC seven-speed automatic transmission. This transmission, a hallmark of Mercedes-Benz engineering, offers smooth and precise gear changes. It features a torque converter lockup clutch to improve efficiency at cruising speeds. The 7G-TRONIC is electronically controlled and adapts its shift points based on driving style and road conditions. The transmission is designed to handle the high torque output of the diesel engine while providing a comfortable and refined driving experience. The 4MATIC all-wheel-drive system distributes power to all four wheels, enhancing traction and stability, particularly in adverse weather conditions.

Fuel Injection and Valvetrain

The OM 642.930 engine employs a third-generation common rail direct injection system. This system delivers fuel directly into the combustion chamber at extremely high pressure, resulting in improved combustion efficiency and reduced emissions. The precise control of fuel injection allows for optimized engine performance and reduced noise. The engine utilizes a double overhead camshaft (DOHC) valvetrain, ensuring efficient cylinder filling and exhaust scavenging. The four valves per cylinder contribute to increased power output and improved engine breathing.

Driving Characteristics

The S 350 CDI BlueEFFICIENCY 4MATIC delivers a refined and comfortable driving experience. The abundant torque from the diesel engine provides strong acceleration, allowing for effortless overtaking and merging onto highways. While not as overtly sporty as the higher-powered S-Class models, the S 350 CDI offers ample performance for most driving situations. Acceleration from 0 to 100 km/h (0-62 mph) takes approximately 7.8 seconds, and 0-60 mph is achieved in around 7.4 seconds. The 7G-TRONIC transmission contributes to smooth and seamless gear changes, enhancing the overall driving experience. The 4MATIC all-wheel-drive system provides enhanced traction and stability, particularly on slippery surfaces. Compared to the S 300 CDI, the S 350 CDI offers a noticeable performance increase, while remaining more fuel-efficient than the larger displacement S 500 models.

Equipment & Trim Levels

The S 350 CDI BlueEFFICIENCY 4MATIC came standard with a comprehensive array of luxury features. Standard equipment typically included leather upholstery, power-adjustable front seats with memory function, dual-zone automatic climate control, a premium audio system, and a multi-function steering wheel. The interior was characterized by high-quality materials and meticulous craftsmanship. Optional extras included features such as a panoramic sunroof, rear seat entertainment system, massaging seats, and advanced driver-assistance systems like Distronic Plus adaptive cruise control and Lane Keeping Assist. The dashboard layout was typical of the W221 S-Class, featuring a combination of analog gauges and a central display screen for infotainment and vehicle settings. Exterior styling was consistent with the facelifted W221 S-Class, featuring revised headlights, taillights, and front and rear bumpers.

Chassis & Braking

The S 350 CDI BlueEFFICIENCY 4MATIC features a fully independent suspension system, providing a comfortable and controlled ride. The front suspension utilizes a multi-link design, while the rear suspension employs a multi-link setup with air suspension. The air suspension system allows for adjustable ride height and damping, further enhancing ride comfort. The braking system consists of disc brakes on all four wheels, providing ample stopping power. Anti-lock braking system (ABS) and electronic stability control (ESP) are standard features, enhancing safety and stability. The steering system is a rack-and-pinion type with power assistance, providing precise and responsive steering feel. The vehicle rides on 235/55 R17 tires mounted on 17-inch alloy wheels.

Market Reception & Comparison

The S 350 CDI BlueEFFICIENCY 4MATIC was generally well-received by automotive critics. It was praised for its blend of luxury, performance, and fuel efficiency. The diesel engine was noted for its strong torque output and refined operation. The 7G-TRONIC transmission was lauded for its smooth and seamless gear changes. The 4MATIC all-wheel-drive system was appreciated for its enhanced traction and stability. Compared to the S 300 CDI, the S 350 CDI offered a noticeable performance improvement without sacrificing fuel economy. Compared to the S 500, the S 350 CDI provided a more fuel-efficient alternative, albeit with slightly less overall power. Fuel economy figures ranged from 7.8-8.0 l/100 km (30.2-29.4 US mpg) combined, and CO2 emissions were rated at 207-211 g/km.

Technical Specifications

Legacy

The OM 642 engine family, including the OM 642.930 found in the S 350 CDI, is known for its durability and reliability. When properly maintained, these engines can accumulate high mileage with minimal issues. The 7G-TRONIC transmission is also generally considered a robust and reliable unit. In the used car market, the W221 S 350 CDI BlueEFFICIENCY 4MATIC represents a compelling value proposition. It offers the prestige and luxury of an S-Class at a more affordable price point than its higher-powered siblings. However, potential buyers should be aware of the potential maintenance costs associated with a complex vehicle like the S-Class, including air suspension components and electronic systems. Regular servicing and preventative maintenance are crucial to ensuring the long-term reliability of this model.