The Mercedes-Benz W123, produced from July 1975 to November 1985, represents a pivotal generation in the lineage of the Mercedes-Benz E-Class. Serving as the successor to the W114 and W115 models, the W123 established new benchmarks for safety, comfort, and engineering refinement in the mid-size executive car segment. While sold globally, the W123 found significant success in Europe and North America, becoming synonymous with German automotive quality and durability. The 300 D Automatic variant, powered by a robust diesel engine, was a particularly popular choice for those prioritizing fuel efficiency and longevity.
The Mercedes-Benz W123 300 D: A Legacy of Engineering
The W123 series was a comprehensive redesign, moving away from the more rounded styling of its predecessors towards a more angular, modern aesthetic. This generation introduced numerous advancements in passive safety, including crumple zones, side-impact protection, and a reinforced passenger cell. The 300 D, specifically, was a key model within the range, offering a diesel-powered alternative that resonated with buyers seeking economical operation without sacrificing the Mercedes-Benz driving experience. It was a car built to last, and many examples remain on the road today, a testament to its robust construction.
Engine & Performance
The heart of the W123 300 D is its OM 617 D 30 inline-five cylinder diesel engine, displacing 3.0 liters (183.38 cubic inches). This naturally aspirated engine produces 80 horsepower at 4000 rpm and 172 Nm (126.86 lb-ft) of torque at 2400 rpm. While not a performance-oriented vehicle, the 300 D’s torque output provides ample pulling power for comfortable cruising and everyday driving. The engine utilizes precombustion chamber injection, a technology common in Mercedes-Benz diesels of the era, contributing to its efficiency and relatively quiet operation for a diesel. Power delivery is managed through a four-speed automatic transmission, sending power to the rear wheels. Acceleration from 0 to 100 km/h (0-62 mph) takes approximately 20.8 seconds, and 0 to 60 mph is achieved in around 19.8 seconds. The top speed is rated at 143 km/h (88.86 mph). Fuel economy is a strong point, achieving approximately 10.4 l/100 km (22.6 US mpg) in urban driving and 8.8 l/100 km (26.7 US mpg) on the open road.
Design & Features
The W123 300 D is a four-door sedan with a classic three-box design. Its exterior is characterized by clean lines, a relatively upright grille, and prominent headlights. The interior is spacious and well-appointed, offering seating for five passengers. The emphasis was on practicality and durability, with high-quality materials used throughout the cabin. Features included power steering, disc brakes on all four wheels, and a comfortable ride thanks to its double wishbone front suspension and trailing arm rear suspension. While not equipped with the advanced electronic systems found in modern vehicles, the W123 prioritized core safety features and a refined driving experience. The car’s robust build quality and relatively simple mechanical design contribute to its enduring appeal among enthusiasts and collectors. The 65-liter (17.17 US gal) fuel tank provides a substantial driving range, further enhancing its suitability for long journeys.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | W123 |
| Generation | W123 |
| Type (Engine) | 300 D (80 Hp) Automatic |
| Start of production | July, 1975 |
| End of production | November, 1985 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 10.4 l/100 km (22.6 US mpg) |
| Fuel consumption (extra urban) | 8.8 l/100 km (26.7 US mpg) |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 20.8 sec |
| Acceleration 0 – 62 mph | 20.8 sec |
| Acceleration 0 – 60 mph | 19.8 sec |
| Maximum speed | 143 km/h (88.86 mph) |
| Weight-to-power ratio | 18.1 kg/Hp |
| Weight-to-torque ratio | 8.4 kg/Nm |
| Power | 80 Hp @ 4000 rpm |
| Torque | 172 Nm @ 2400 rpm (126.86 lb.-ft. @ 2400 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | OM 617 D 30 / 617.912 |
| Engine displacement | 3005 cm3 (183.38 cu. in.) |
| Number of cylinders | 5 |
| Engine configuration | Inline |
| Cylinder Bore | 91 mm (3.58 in.) |
| Piston Stroke | 92.4 mm (3.64 in.) |
| Compression ratio | 21.5:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Precombustion chamber injection |
| Engine aspiration | Naturally aspirated |
| Valvetrain | SOHC |
| Engine oil capacity | 7.5 l (7.93 US qt | 6.6 UK qt) |
| Coolant capacity | 11 l (11.62 US qt | 9.68 UK qt) |
| Kerb Weight | 1450 kg (3196.7 lbs.) |
| Max. weight | 1970 kg (4343.11 lbs.) |
| Max load | 520 kg (1146.4 lbs.) |
| Fuel tank capacity | 65 l (17.17 US gal | 14.3 UK gal) |
| Length | 4725 mm (186.02 in.) |
| Width | 1786 mm (70.31 in.) |
| Height | 1438 mm (56.61 in.) |
| Wheelbase | 2795 mm (110.04 in.) |
| Front track | 1488 mm (58.58 in.) |
| Rear track | 1446 mm (56.93 in.) |
| Drivetrain | Rear wheel drive |
| Number of gears | 4 |
| Gearbox type | Automatic transmission |
| Front suspension | Double wishbone |
| Rear suspension | Trailing arm |
| Front brakes | Disc |
| Rear brakes | Disc |
| Steering type | Cone worm with recirculation balls |
| Power steering | Hydraulic |
| Wheel rims size | 5.5J x 14 |
The Mercedes-Benz W123 300 D Automatic remains a highly regarded vehicle, celebrated for its durability, comfort, and timeless design. It represents a significant chapter in Mercedes-Benz history, embodying the brand’s commitment to engineering excellence and setting a high standard for mid-size luxury sedans.
