The Mercedes-Benz S-Class (W220 facelift), produced from 2002 to 2005, represented a significant mid-cycle refresh of the flagship S-Class sedan. The S 320 CDI, equipped with a 3.2-liter turbocharged diesel engine and a 5G-TRONIC automatic transmission, occupied a middle ground within the W220 lineup, positioned between the entry-level S 320 gasoline model and the higher-performance S 430 and S 500 variants. This variant aimed to provide a balance of luxury, fuel efficiency, and respectable performance for discerning buyers.
The S 320 CDI was powered by the OM 648 DE 32 LA engine, a 3.2-liter inline-six cylinder diesel. This engine featured commonrail direct fuel injection, a turbocharger with an intercooler, and four valves per cylinder. The OM648 engine was known for its robust construction and relatively smooth operation for a diesel. The engine produced 204 horsepower at 4200 rpm and a substantial 368.78 lb-ft of torque between 1800 and 2600 rpm. The 5G-TRONIC transmission, a five-speed automatic, was specifically tuned to handle the diesel engine’s torque characteristics. This transmission offered smooth shifts and a driver-selectable manual mode, though it wasn’t geared towards aggressive performance.
In real-world driving, the S 320 CDI offered a comfortable and refined experience. While not as quick as its gasoline-powered siblings, the abundant torque provided strong acceleration, particularly in the mid-range. Acceleration from 0 to 60 mph was achieved in approximately 7.5 seconds, and top speed was electronically limited to 146 mph. The 5G-TRONIC transmission’s gear ratios were optimized for fuel economy and relaxed cruising, rather than outright performance. The engine delivered a quiet and smooth power delivery, making it well-suited for long-distance highway driving.
The S 320 CDI came standard with a comprehensive list of luxury features befitting a flagship Mercedes-Benz. Standard interior appointments included leather upholstery, wood trim, automatic climate control, power-adjustable front seats with memory function, and a premium audio system. Optional extras included rear seat entertainment, massaging seats, a panoramic sunroof, and advanced driver-assistance systems like Distronic adaptive cruise control. The dashboard layout was typical of the W220 facelift, featuring a blend of analog gauges and a central multi-function display.
The S 320 CDI utilized a fully independent suspension system, with multi-link setups at both the front and rear. Front brakes were ventilated discs, while rear brakes were solid discs. Anti-lock braking system (ABS) was standard. The suspension was tuned for comfort, providing a smooth and controlled ride. Steering was handled by a hydraulic power steering rack and pinion system. The car rode on 225/60 R16 tires mounted on 7.5J x 16 inch alloy wheels.
Critics generally praised the S 320 CDI for its fuel efficiency and comfortable ride. The diesel engine offered significantly better fuel economy than the gasoline alternatives, achieving approximately 30.5 US mpg in combined driving. However, some reviewers noted that the performance was not as exhilarating as the higher-powered S-Class models. Reliability was generally good, although the complex diesel fuel injection system and turbocharger could require occasional maintenance. Compared to the S 430 and S 500, the S 320 CDI appealed to buyers prioritizing fuel economy and long-distance comfort over outright speed.
| Engine Model/Code | OM 648 DE 32 LA/648.960 |
| Engine displacement | 3222 cm3 (196.62 cu. in.) |
| Number of cylinders | 6 (Inline) |
| Cylinder Bore | 88 mm (3.46 in.) |
| Piston Stroke | 88.4 mm (3.48 in.) |
| Compression ratio | 18:1 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Power | 204 Hp @ 4200 rpm |
| Torque | 500 Nm @ 1800-2600 rpm (368.78 lb.-ft.) |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 7.9 sec |
| Acceleration 0 – 60 mph | 7.5 sec |
| Maximum speed | 235 km/h (146.02 mph) |
| Fuel consumption (urban) | 11 l/100 km (21.4 US mpg) |
| Fuel consumption (extra urban) | 5.8 l/100 km (40.6 US mpg) |
| Fuel consumption (combined) | 7.7 l/100 km (30.5 US mpg) |
| CO2 emissions | 204 g/km |
| Kerb Weight | 1850 kg (4078.55 lbs.) |
| Fuel tank capacity | 88 l (23.25 US gal) |
| Trunk (boot) space | 500 l (17.66 cu. ft.) |
| Number of gears | 5 |
| Gearbox type | Automatic transmission |
| Length | 5043 mm (198.54 in.) |
| Width | 1855 mm (73.03 in.) |
Today, the W220 S 320 CDI is a relatively affordable entry point into the world of Mercedes-Benz luxury. The OM648 diesel engine, while requiring diligent maintenance, is known for its longevity. Finding well-maintained examples can be challenging, as age and mileage take their toll. However, for buyers seeking a comfortable, fuel-efficient, and relatively reliable luxury sedan, the S 320 CDI remains a compelling option in the used car market. Parts availability is generally good, and the car’s robust construction ensures that it can provide many more years of service with proper care.
