The Mercedes-Benz M-Class (W164), particularly the facelifted version introduced in 2008, represented a significant step forward for the German automaker in the burgeoning mid-size luxury SUV segment. The ML 320 CDI 4MATIC, equipped with a 3.0-liter V6 turbodiesel engine and a 7G-TRONIC automatic transmission, was a key variant offered from 2008 to 2009. This model aimed to balance fuel efficiency, respectable performance, and the all-weather capability expected of a Mercedes-Benz SUV. It occupied a middle ground in the W164 lineup, positioned below the more powerful ML 500 and above the entry-level ML 350.
| Brand | Mercedes-Benz |
| Model | M-Class |
| Generation | M-Class (W164, facelift 2008) |
| Type (Engine) | ML 320 CDI V6 (224 Hp) 4MATIC 7G-TRONIC |
| Start of production | 2008 |
| End of production | 2009 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | SUV |
| Seats | 5 |
| Doors | 5 |
| Fuel consumption (urban) | 11.9-12.8 l/100 km (19.8 – 18.4 US mpg) |
| Fuel consumption (extra urban) | 7.8 l/100 km (30.2 US mpg) |
| Fuel consumption (combined) | 9.3-9.6 l/100 km (25.3 – 24.5 US mpg) |
| CO2 emissions | 245-254 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 8.6 sec |
| Acceleration 0 – 60 mph | 8.2 sec |
| Maximum speed | 215 km/h (133.59 mph) |
| Emission standard | Euro 4 |
| Weight-to-power ratio | 9.4 kg/Hp |
| Weight-to-torque ratio | 4.1 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 642.940 |
| 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.) |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Valvetrain | DOHC |
| Engine oil capacity | 8.5 l (8.98 US qt | 7.48 UK qt) |
| Coolant capacity | 9.5 l (10.04 US qt | 8.36 UK qt) |
| Kerb Weight | 2110 kg (4651.75 lbs.) |
| Max. weight | 2830 kg (6239.08 lbs.) |
| Max load | 720 kg (1587.33 lbs.) |
| Trunk (boot) space (min) | 833 l (29.42 cu. ft.) |
| Trunk (boot) space (max) | 2050 l (72.4 cu. ft.) |
| Fuel tank capacity | 95 l (25.1 US gal | 20.9 UK gal) |
| Max. roof load | 100 kg (220.46 lbs.) |
| Permitted trailer load (braked) | 3500 kg (7716.18 lbs.) |
| Permitted trailer load (unbraked) | 750 kg (1653.47 lbs.) |
| Length | 4781 mm (188.23 in.) |
| Width | 1911 mm (75.24 in.) |
| Width including mirrors | 2124 mm (83.62 in.) |
| Height | 1815 mm (71.46 in.) |
| Wheelbase | 2915 mm (114.76 in.) |
| Front track | 1627 mm (64.06 in.) |
| Rear track | 1629 mm (64.13 in.) |
| Ride height (ground clearance) | 210 mm (8.27 in.) |
| Drag coefficient (Cd) | 0.35 |
| Minimum turning circle | 11.6 m (38.06 ft.) |
| Front suspension | Double wishbone, Transverse stabilizer |
| Rear suspension | Independent multi-link suspension, Transverse stabilizer |
| Front brakes | Ventilated discs |
| Rear brakes | Disc |
| Gearbox | 7 gears, automatic transmission G-TRONIC |
Powertrain & Engine Architecture
The heart of the ML 320 CDI was the OM 642.940 3.0-liter V6 turbodiesel engine. This engine was a cornerstone of Mercedes-Benz’s diesel offerings during the late 2000s, known for its robust construction and relatively sophisticated technology. It featured a common rail direct injection system, delivering fuel at extremely high pressures for optimized combustion. The engine utilized a variable geometry turbocharger (VGT) and an intercooler to enhance power and efficiency. The VGT allowed the turbocharger to adjust its vanes based on engine speed and load, providing strong low-end torque and improved responsiveness. The 7G-TRONIC automatic transmission, a seven-speed unit, was paired with the engine. This transmission was lauded for its smooth shifting and wide gear ratios, contributing to both fuel economy and performance. The 7G-TRONIC featured a torque converter lock-up clutch that engaged in most gears, reducing slippage and improving efficiency.
Driving Characteristics
The ML 320 CDI 4MATIC offered a comfortable and capable driving experience. While not a sports SUV, the 224 horsepower and 376 lb-ft of torque provided adequate acceleration, with a 0-60 mph time of around 8.2 seconds. The 7G-TRONIC transmission played a crucial role in delivering power smoothly and efficiently. The automatic transmission was tuned for comfort, with relatively relaxed shift points. Compared to the ML 350 with its gasoline V6, the ML 320 CDI offered significantly more torque at lower engine speeds, making it feel more effortless when towing or navigating hilly terrain. Compared to the higher-output ML 500, the 320 CDI prioritized fuel economy and usability over outright speed. The 4MATIC all-wheel-drive system provided excellent traction in various weather conditions, enhancing stability and control.
Equipment & Trim Levels
The ML 320 CDI 4MATIC typically came well-equipped, reflecting its position as a luxury SUV. Standard features included leather upholstery, power-adjustable front seats with memory function, dual-zone automatic climate control, a premium audio system, and a sunroof. Safety features were also comprehensive, including anti-lock brakes (ABS), electronic stability control (ESP), and multiple airbags. Optional extras included navigation system, rear-seat entertainment system, parking assist, and upgraded interior trim options. The interior design was typical of Mercedes-Benz at the time, emphasizing quality materials and a refined aesthetic.
Chassis & Braking
The W164 M-Class featured an independent suspension system all around, with double wishbones at the front and a multi-link setup at the rear. This configuration provided a comfortable ride and good handling characteristics. Stabilizer bars were fitted to both axles to reduce body roll during cornering. The braking system consisted of ventilated discs at the front and solid discs at the rear. ABS and ESP were standard, enhancing braking performance and stability. The 4MATIC all-wheel-drive system utilized a multi-plate clutch to distribute torque between the front and rear axles, providing optimal traction in various conditions.
Market Reception & Comparison
The ML 320 CDI 4MATIC was generally well-received by automotive critics. It was praised for its fuel efficiency, comfortable ride, and capable all-wheel-drive system. However, some reviewers noted that the diesel engine could be somewhat noisy compared to gasoline alternatives. Compared to the ML 350, the 320 CDI offered better fuel economy and more low-end torque, making it a more practical choice for those who frequently tow or drive in challenging conditions. Against competitors like the BMW X5 and Audi Q7, the ML 320 CDI offered a compelling combination of luxury, performance, and fuel efficiency.
Legacy
The OM 642 engine family, including the version used in the ML 320 CDI, has proven to be remarkably durable and reliable. While diesel engines generally require more diligent maintenance than their gasoline counterparts, these engines are known to withstand high mileage with proper care. Today, well-maintained examples of the ML 320 CDI 4MATIC can still be found on the used car market, offering a relatively affordable entry point into the Mercedes-Benz SUV experience. Common issues include wear and tear on the turbocharger, potential problems with the glow plugs, and the occasional need for diesel particulate filter (DPF) maintenance. However, these issues are generally manageable with regular servicing and preventative maintenance.
