The Mercedes-Benz S 350d 4MATIC, produced from 2020 to April 2023, represents a significant iteration of the W223 generation S-Class. Positioned as a diesel-powered variant within the flagship luxury sedan lineup, it offered a blend of performance, efficiency, and advanced technology. This model served as a compelling alternative to the gasoline-powered S 450 and the high-performance S 580, appealing to buyers prioritizing fuel economy and torque without sacrificing the S-Class’s renowned comfort and refinement. The S 350d 4MATIC utilized a sophisticated diesel engine paired with a 9-speed automatic transmission and Mercedes-Benz’s 4MATIC all-wheel-drive system, making it a popular choice in European and Asian markets.
Powertrain & Engine Architecture
The heart of the S 350d 4MATIC is the OM 656.929, a 2.9-liter inline-six cylinder diesel engine. This engine is a cornerstone of Mercedes-Benz’s modern diesel offerings, known for its robust construction and advanced technology. It features a sophisticated diesel commonrail fuel injection system, delivering precise fuel metering for optimized combustion. The engine employs a bi-turbocharger setup with an intercooler, enhancing both power and torque output. The valvetrain utilizes a Double Overhead Camshaft (DOHC) configuration with four valves per cylinder, contributing to efficient gas exchange and improved engine breathing.
The engine produces 286 horsepower at 3400-4600 rpm and a substantial 600 Nm (442.54 lb-ft) of torque between 1200-3200 rpm. This broad torque curve provides effortless acceleration and strong pulling power, particularly useful for highway cruising and overtaking. The engine also incorporates a Start & Stop system for improved fuel efficiency in urban driving conditions and a particulate filter to minimize emissions, adhering to stringent Euro 6D-ISC-FCM emission standards.
The engine is mated to a 9G-TRONIC automatic transmission. This nine-speed automatic is designed for smooth and efficient gear changes, contributing to both performance and fuel economy. The transmission features a wide gear ratio spread, allowing the engine to operate within its optimal efficiency range more frequently. The 4MATIC all-wheel-drive system provides enhanced traction and stability, particularly in adverse weather conditions. The system operates with a rear-wheel bias, maintaining the traditional Mercedes-Benz driving feel while providing added security when needed.
Engine Specifications
Engine Code: OM 656.929
Displacement: 2925 cm³ (178.49 cu. in.)
Compression Ratio: 15.5:1
Engine Oil Capacity: 8.5 liters (8.98 US qt | 7.48 UK qt)
Driving Characteristics
The S 350d 4MATIC delivers a refined and comfortable driving experience. The abundant torque from the diesel engine provides strong acceleration, with a 0-100 km/h (0-62 mph) time of 6.2 seconds and a 0-60 mph time of approximately 5.9 seconds. While not as overtly sporty as the gasoline-powered S-Class models, the S 350d offers ample power for confident highway cruising and effortless overtaking. The 9G-TRONIC transmission shifts smoothly and responsively, contributing to a relaxed driving experience.
Compared to the S 450, the S 350d prioritizes torque over outright horsepower. This translates to a more relaxed and effortless driving style, particularly at lower speeds. The S 350d also offers significantly better fuel economy than its gasoline counterparts. Compared to higher-performance variants like the S 580, the S 350d provides a more balanced driving experience, offering a good compromise between performance, efficiency, and comfort. The all-wheel-drive system enhances stability and traction, making it a confident performer in various weather conditions.
Equipment & Trim Levels
The S 350d 4MATIC came standard with a comprehensive array of luxury features, befitting its flagship status. Standard equipment typically included leather upholstery, heated and ventilated front seats with massage functions, a premium sound system, a large infotainment display with Mercedes-Benz’s MBUX system, and a suite of advanced driver-assistance systems. These systems included adaptive cruise control, lane-keeping assist, automatic emergency braking, and a 360-degree camera system.
Optional extras were extensive, allowing buyers to personalize their S-Class to their specific preferences. These options included upgraded leather upholstery, a panoramic sunroof, rear-seat entertainment systems, and various interior trim packages. The S 350d 4MATIC was often equipped with the AIRMATIC air suspension system, providing a supremely comfortable ride quality. The interior dashboard configuration was consistent across the W223 range, featuring a dual-screen setup for the instrument cluster and infotainment system.
Chassis & Braking
The S 350d 4MATIC utilizes an independent multi-link suspension system both front and rear, often paired with the AIRMATIC air suspension. The AIRMATIC system allows for adjustable ride height and damping, providing a customizable driving experience. The suspension is tuned to prioritize comfort and refinement, absorbing bumps and imperfections in the road surface effectively. Stabilizer bars are employed to minimize body roll during cornering.
The braking system consists of ventilated discs on all four wheels, providing ample stopping power. Anti-lock braking system (ABS) is standard, along with electronic brake-force distribution and brake assist. The S-Class also features a 4-wheel steering system (4WS), enhancing maneuverability at low speeds and stability at high speeds. Tire sizes varied depending on the wheel size, ranging from 255/50 R18 to 285/35 R20.
Market Reception & Comparison
The S 350d 4MATIC was generally well-received by automotive critics, praised for its blend of performance, efficiency, and luxury. Reviewers highlighted the engine’s strong torque output, smooth transmission, and comfortable ride quality. Fuel economy was a significant selling point, with the S 350d offering considerably better mileage than its gasoline-powered counterparts.
Compared to the S 450, the S 350d appealed to buyers prioritizing fuel efficiency and low-end torque. While the S 450 offered more horsepower, the S 350d provided a more relaxed and effortless driving experience. In terms of reliability, the OM 656 diesel engine has proven to be a robust and dependable unit, although diesel engines generally require more diligent maintenance than gasoline engines. The S 350d 4MATIC represented a compelling value proposition within the S-Class range, offering a luxurious and refined experience at a more accessible price point.
Technical Specifications
| Body Type | Sedan, 4 Doors, 5 Seats |
| Fuel Economy (Combined WLTP) | 6.5-7.9 l/100 km (36.2 – 29.8 US mpg, 43.5 – 35.8 UK mpg, 15.4 – 12.7 km/l) |
| CO2 Emissions (WLTP) | 171-209 g/km |
| Acceleration 0-100 km/h | 6.2 sec |
| Acceleration 0-62 mph | 6.2 sec |
| Acceleration 0-60 mph | 5.9 sec (Calculated) |
| Maximum Speed | 250 km/h (155.34 mph) – Electronically Limited |
| Emission Standard | Euro 6D-ISC-FCM |
| Weight-to-Power Ratio | 7 kg/Hp |
| Weight-to-Torque Ratio | 3.3 kg/Nm |
| Engine Layout | Front, Longitudinal |
| Engine Displacement | 2925 cm³ (178.49 cu. in.) |
| Number of Cylinders | 6 (Inline) |
| Cylinder Bore | 82 mm (3.23 in.) |
| Piston Stroke | 92.4 mm (3.64 in.) |
| Fuel Injection System | Diesel Commonrail |
| Engine Aspiration | BiTurbo, Intercooler |
| Kerb Weight | 1995 kg (4398.22 lbs.) |
| Max. Weight | 2770 kg (6106.8 lbs.) |
| Trunk (Boot) Space | 540 l (19.07 cu. ft.) |
| Fuel Tank Capacity | 65 l (17.17 US gal | 14.3 UK gal) |
| Gearbox | 9 gears, automatic transmission G-TRONIC |
| Front Track | 1660 mm (65.35 in.) |
| Rear Track | 1688 mm (66.46 in.) |
| Length | 5179 mm (203.9 in.) |
| Width | 1921-1954 mm (75.63 – 76.93 in.) |
| Height | 1503 mm (59.17 in.) |
Legacy
The OM 656 diesel engine, as featured in the S 350d 4MATIC, has established a reputation for reliability and longevity. With proper maintenance, these engines are capable of accumulating high mileage without major issues. In the used car market, the S 350d 4MATIC represents a compelling value proposition, offering a luxurious and well-equipped S-Class at a more affordable price point than its gasoline-powered counterparts. The combination of strong performance, excellent fuel economy, and a comfortable driving experience continues to make it a desirable option for buyers seeking a refined and efficient luxury sedan.
