The Mercedes-Benz C-Class (W204) C 320 CDI V6 7G-TRONIC, produced from 2007 to 2009, represented a compelling blend of performance and efficiency within the broader W204 C-Class range. Positioned as a mid-to-upper tier offering, it catered to buyers seeking a refined diesel experience with strong acceleration and comfortable long-distance cruising. This variant occupied a space between the more economical C 220 CDI and the higher-performance C 350 models, appealing to those prioritizing torque and fuel economy without sacrificing luxury. The W204 generation itself was a significant step forward for Mercedes-Benz, introducing a more modern design language and improved build quality compared to its predecessor.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | C-class |
| Generation | C-class (W204) |
| Type (Engine) | C 320 CDI V6 (224 Hp) 7G-TRONIC |
| Start of production | 2007 |
| End of production | 2009 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 10-10.3 l/100 km (23.5 – 22.8 US mpg) |
| Fuel consumption (extra urban) | 5.9-6.2 l/100 km (39.9 – 37.9 US mpg) |
| Fuel consumption (combined) | 7.3-7.6 l/100 km (32.2 – 30.9 US mpg) |
| CO2 emissions | 193-201 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 6.9 sec |
| Acceleration 0 – 62 mph | 6.9 sec |
| Acceleration 0 – 60 mph | 6.6 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Emission standard | Euro 4 |
| Weight-to-power ratio | 7.3 kg/Hp |
| Weight-to-torque ratio | 3.2 kg/Nm |
| Power | 224 Hp @ 3800 rpm |
| Torque | 510 Nm @ 1600-2800 rpm (376.16 lb.-ft.) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | OM 642.960 |
| Engine displacement | 2987 cm3 (182.28 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | V-engine |
| Cylinder Bore | 83 mm (3.27 in.) |
| Piston Stroke | 92 mm (3.62 in.) |
| Compression ratio | 17.7:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Valvetrain | DOHC |
| Engine oil capacity | 8 l (8.45 US qt | 7.04 UK qt) |
| Kerb Weight | 1625 kg (3582.51 lbs.) |
| Max. weight | 2185 kg (4817.1 lbs.) |
| Max load | 560 kg (1234.59 lbs.) |
| Trunk (boot) space | 475 l (16.77 cu. ft.) |
| Fuel tank capacity | 66 l (17.44 US gal | 14.52 UK gal) |
| Permitted trailer load (braked) | 1800 kg (3968.32 lbs.) |
| Permitted trailer load (unbraked) | 750 kg (1653.47 lbs.) |
| Length | 4581 mm (180.35 in.) |
| Width | 1770 mm (69.69 in.) |
| Width (with mirrors) | 2020 mm (79.53 in.) |
| Height | 1447 mm (56.97 in.) |
| Wheelbase | 2760 mm (108.66 in.) |
| Front track | 1549 mm (60.98 in.) |
| Rear track | 1552 mm (61.1 in.) |
| Front overhang | 765 mm (30.12 in.) |
| Rear overhang | 1056 mm (41.57 in.) |
| Drag coefficient (Cd) | 0.29 |
| Turning circle | 10.84 m (35.56 ft.) |
| Drivetrain | Rear wheel drive |
| Gearbox | 7 gears, automatic transmission 7G-TRONIC |
| Front suspension | Independent type McPherson, Transverse stabilizer |
| Rear suspension | Independent multi-link suspension, Transverse stabilizer |
| Front brakes | Ventilated discs |
| Rear brakes | Disc |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Power steering | Hydraulic |
| Tires size | 225/45 R17 |
| Wheel rims size | 7.5J x 17 |
Powertrain & Engine Architecture
The heart of the C 320 CDI was the OM 642.960 3.0-liter V6 turbodiesel engine. This engine was a cornerstone of Mercedes-Benz’s diesel offerings during the mid-2000s, known for its robust construction and refined operation. It featured a common rail direct injection system, delivering fuel at extremely high pressures for optimized combustion. The engine employed a variable geometry turbocharger (VGT) and an intercooler to maximize power and efficiency. The V6 configuration contributed to smoother operation compared to inline engines, and the DOHC (Double Overhead Camshaft) valvetrain, with four valves per cylinder, further enhanced breathing and performance. Paired with the engine was the 7G-TRONIC seven-speed automatic transmission. This transmission was lauded for its smooth shifts and wide gear ratio spread, contributing to both fuel economy and responsive acceleration. The 7G-TRONIC allowed the engine to operate within its optimal power band more frequently.
Driving Characteristics
The C 320 CDI 7G-TRONIC offered a distinctly different driving experience compared to its gasoline-powered siblings or even the lower-powered diesel variants. The substantial 376 lb-ft of torque, available from a low 1600 rpm, provided effortless acceleration in everyday driving situations. While not as overtly sporty as the C 350, the C 320 CDI delivered a strong and confident surge of power, particularly during overtaking maneuvers. The 7G-TRONIC transmission’s programming prioritized smooth shifts and fuel efficiency, but also offered a manual mode for more driver control. The gear ratios were well-matched to the engine’s torque curve, ensuring that power was readily available across a wide speed range. Compared to the six-speed manual transmissions offered on other C-Class models, the 7G-TRONIC provided a more relaxed and refined driving experience, especially on long journeys.
Equipment & Trim Levels
The C 320 CDI typically came well-equipped, reflecting its position in the C-Class lineup. Standard features generally included automatic climate control, power-adjustable front seats, a multi-function steering wheel, and a premium audio system. Interior upholstery was typically a combination of leatherette and fabric, with full leather options available as an upgrade. Optional extras included a sunroof, navigation system, upgraded audio systems (such as Harman Kardon), and parking sensors. The dashboard layout was typical of the W204 C-Class, featuring a dual-tone color scheme and a central display screen for infotainment and vehicle settings.
Chassis & Braking
The C 320 CDI utilized a fully independent suspension system, with McPherson struts at the front and a multi-link setup at the rear. This configuration provided a good balance between ride comfort and handling precision. Stabilizer bars were fitted to both axles to reduce body roll during cornering. Braking duties were handled by ventilated discs at the front and solid discs at the rear, equipped with ABS (Anti-lock Braking System) and electronic brake-force distribution. The suspension was tuned to accommodate the slightly higher weight of the diesel engine compared to the gasoline variants, ensuring stable and predictable handling.
Market Reception & Comparison
The C 320 CDI was generally well-received by automotive critics. It was praised for its strong performance, excellent fuel economy, and refined driving experience. However, some reviewers noted that the diesel engine’s inherent noise and vibration were more noticeable than in some competitor vehicles. Compared to the C 220 CDI, the C 320 CDI offered a significant performance upgrade, justifying its higher price tag for buyers prioritizing power. Against the C 350, the C 320 CDI provided comparable acceleration but with significantly better fuel economy. Reliability was generally good, although diesel particulate filter (DPF) issues could arise with infrequent long-distance driving.
Legacy
The OM 642 engine family, including the version found in the C 320 CDI, has proven to be remarkably durable. Well-maintained examples continue to provide reliable service today. The 7G-TRONIC transmission is also known for its longevity, although regular fluid changes are essential. In the used car market, the W204 C 320 CDI represents a compelling value proposition for buyers seeking a comfortable, efficient, and relatively powerful luxury sedan. Its combination of performance, economy, and build quality has ensured its continued popularity among discerning drivers.
