The Mercedes-Benz R-Class (W251) R 300 CDI V6 4MATIC G-TRONIC, produced from 2009 to 2010, represents a unique offering within the luxury SUV/wagon segment. Positioned as a spacious, versatile vehicle, the R-Class aimed to blend the practicality of a station wagon with the prestige and capabilities of a Mercedes-Benz SUV. This particular variant, powered by the OM 642.950 3.0-liter V6 turbodiesel engine and paired with the 7G-TRONIC automatic transmission, was a key model in the R-Class lineup, offering a balance between performance, fuel efficiency, and all-weather capability thanks to its 4MATIC all-wheel-drive system. It was primarily marketed in Europe and other regions where larger wagons and diesel engines were more popular.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | R-class |
| Generation | R-class (W251) |
| Type (Engine) | R 300 CDI V6 (190 Hp) 4MATIC G-TRONIC |
| Start of production | 2009 |
| End of production | 2010 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Station wagon (estate) |
| Seats | 5 |
| Doors | 5 |
| Fuel consumption (combined) | 8.5 l/100 km (27.7 US mpg, 33.2 UK mpg, 11.8 km/l) |
| CO2 emissions | 246 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 9.9 sec |
| Acceleration 0 – 62 mph | 9.9 sec |
| Acceleration 0 – 60 mph | 9.4 sec |
| Maximum speed | 210 km/h (130.49 mph) |
| Emission standard | Euro 5 |
| Weight-to-power ratio | 11.8 kg/Hp, 84.4 Hp/tonne |
| Weight-to-torque ratio | 5.1 kg/Nm, 195.6 Nm/tonne |
| Power | 190 Hp @ 3800 rpm |
| Power per litre | 63.6 Hp/l |
| Torque | 440 Nm @ 1400-2800 rpm (324.53 lb.-ft. @ 1400-2800 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | OM 642.950 |
| Engine displacement | 2987 cm3 (182.28 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | V-engine |
| Compression ratio | 15.5:1 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Engine oil capacity | 8.5 l (8.98 US qt | 7.48 UK qt) |
| Coolant capacity | 10.1 l (10.67 US qt | 8.89 UK qt) |
| Kerb Weight | 2250 kg (4960.4 lbs) |
| Max. weight | 2840 kg (6261.13 lbs) |
| Max load | 590 kg (1300.73 lbs) |
| Trunk (boot) space – minimum | 550 l (19.42 cu. ft.) |
| Trunk (boot) space – maximum | 1950 l (68.86 cu. ft.) |
| Fuel tank capacity | 80 l (21.13 US gal | 17.6 UK gal) |
| Permitted trailer load with brakes (12%) | 2100 kg (4629.71 lbs) |
| Permitted trailer load without brakes | 750 kg (1653.47 lbs) |
| Length | 4922 mm (193.78 in) |
| Width | 1922 mm (75.67 in) |
| Height | 1657 mm (65.24 in) |
| Wheelbase | 2980 mm (117.32 in) |
| Front track | 1661 mm (65.39 in) |
| Rear (Back) track | 1651 mm (65 in) |
| Minimum turning circle | 11.8 m (38.71 ft) |
| Drive wheel | All wheel drive (4×4) |
| Number of gears and type of gearbox | 7 gears, automatic transmission G-TRONIC |
| Front suspension | Double wishbone |
| 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 |
| Tires size | 235/65 R17 |
| Wheel rims size | 17 |
Powertrain & Engine Architecture
The heart of the R 300 CDI 4MATIC is the OM 642.950 3.0-liter V6 diesel engine. This engine is a member of the OM 642 family, known for its robust construction and relatively quiet operation for a diesel. It features a common rail direct injection system, delivering fuel at extremely high pressures for optimized combustion. A variable geometry turbocharger (VGT) and intercooler further enhance performance and efficiency. The engine produces 190 horsepower at 3800 rpm and a substantial 440 Nm (324.53 lb-ft) of torque between 1400 and 2800 rpm. This broad torque curve is a hallmark of diesel engines, providing strong pulling power at lower engine speeds. The engine also incorporates a diesel particulate filter (DPF) to reduce emissions, meeting Euro 5 standards. The 7G-TRONIC automatic transmission, a seven-speed unit, provides smooth and efficient gear changes. It’s known for its adaptability and contributes to both fuel economy and driving comfort.
Driving Characteristics
The R 300 CDI 4MATIC offers a comfortable and refined driving experience. While not a sports car, the engine’s torque output provides ample acceleration for everyday driving and highway cruising. The 0-60 mph time of around 9.4 seconds is respectable for a large wagon. The 7G-TRONIC transmission is well-matched to the engine, providing seamless shifts and helping to keep the engine in its optimal power band. Compared to the more powerful R 350 models, the R 300 CDI prioritizes fuel economy and relaxed cruising. Manual transmission options were not available in this configuration. The 4MATIC all-wheel-drive system provides excellent traction in various weather conditions, enhancing stability and safety. The steering is precise, but lacks significant feedback.
Equipment & Trim Levels
The R 300 CDI 4MATIC typically came well-equipped, reflecting its luxury positioning. Standard features included leather upholstery, automatic climate control, a premium audio system, and power-adjustable front seats. Optional extras included a panoramic sunroof, navigation system, rear seat entertainment, and advanced driver-assistance systems like Distronic adaptive cruise control. Trim levels varied by market, but generally offered increasing levels of luxury and technology. The interior design was characterized by Mercedes-Benz’s typical attention to detail and high-quality materials.
Chassis & Braking
The R-Class utilizes a robust chassis designed to handle the vehicle’s weight and provide a comfortable ride. The front suspension features a double wishbone setup, while the rear employs an independent multi-link spring suspension with a stabilizer bar. This configuration provides a good balance between ride comfort and handling. Braking duties are handled by ventilated discs at the front and solid discs at the rear, coupled with an Anti-lock Braking System (ABS). The hydraulic power steering provides precise control, although it lacks the feel of more modern electric systems.
Market Reception & Comparison
The R-Class, in general, received mixed reviews. Critics praised its spacious interior, comfortable ride, and available features, but questioned its styling and somewhat awkward proportions. The R 300 CDI 4MATIC was generally well-regarded for its fuel efficiency and strong torque output. Compared to the R 350, it offered better fuel economy but less outright performance. Against competitors like the BMW X5 and Audi Q7, the R-Class offered a unique blend of wagon practicality and SUV capability, but often struggled to gain significant market share.
Legacy
The OM 642 engine family, including the OM 642.950 found in the R 300 CDI, is known for its durability and reliability. With proper maintenance, these engines can accumulate high mileage. The 7G-TRONIC transmission is also generally reliable, although some units may require servicing over time. On the used car market, the R 300 CDI 4MATIC represents a relatively affordable entry point into the Mercedes-Benz luxury segment. However, potential buyers should be aware of the potential maintenance costs associated with a vehicle of this age and complexity, particularly regarding the DPF and other emissions control systems. The R-Class, while not a commercial success, remains a distinctive and interesting vehicle, showcasing Mercedes-Benz’s willingness to experiment with new vehicle concepts.
