Mercedes-Benz W123 300 D (80 Hp)

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, the W123 established new benchmarks for safety, comfort, and engineering refinement in the mid-size executive car segment. Offered in sedan, coupe, and estate (wagon) body styles, the W123 was a global success, particularly in Europe, where it became synonymous with understated luxury and robust reliability. The 300 D variant, powered by a naturally aspirated diesel engine, was a popular choice for those prioritizing fuel economy and longevity.

Mercedes-Benz W123 300 D: A Detailed Overview

The W123 series was a significant departure from its predecessors, incorporating advancements in crumple zone technology and overall structural integrity. This focus on safety, combined with a comfortable interior and a reputation for durability, cemented the W123’s position as a desirable vehicle for families and discerning drivers alike. While not initially sold in large numbers in the United States due to tightening emissions regulations, the W123 found a strong following among enthusiasts who appreciated its build quality and classic design. The 300 D, in particular, became known for its exceptionally long service life, with many examples remaining on the road today.

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 engine, a hallmark of Mercedes-Benz diesel technology of the era, 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 offered ample torque for comfortable cruising and effortless highway driving. The engine utilizes precombustion chamber injection, a system designed to improve combustion efficiency and reduce emissions. Power delivery is smooth and linear, characteristic of diesel engines. Acceleration from 0 to 60 mph takes approximately 18.9 seconds, and the vehicle reaches a top speed of 148 km/h (91.96 mph). The engine’s robust construction and relatively simple design contributed to its legendary reliability. Fuel economy is a strong point, achieving approximately 22.8 US mpg in urban conditions and 30.2 US mpg on the open road.

Design & Features

The W123 300 D is a four-door sedan with a classic, understated design. Its clean lines, prominent grille, and relatively compact dimensions contribute to its timeless appeal. The interior is characterized by its functional layout, comfortable seating for five passengers, and high-quality materials. While not lavishly equipped by modern standards, the W123 offered a range of features considered luxurious for its time, including power steering, disc brakes on all four wheels, and a four-speed manual transmission. Safety features, a key focus for Mercedes-Benz, included reinforced passenger cell construction and crumple zones designed to absorb impact energy in the event of a collision. The vehicle’s suspension, featuring a double wishbone front setup and a trailing arm rear suspension, provides a comfortable and controlled ride. The 65-liter (17.17 US gal) fuel tank offers a substantial driving range. The W123’s design prioritized practicality and durability, making it a versatile and reliable vehicle for everyday use.

Technical Specifications

Brand Mercedes-Benz
Model W123
Generation W123
Type (Engine) 300 D (80 Hp)
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) 10.3 l/100 km (22.8 US mpg)
Fuel consumption (extra urban) 7.8 l/100 km (30.2 US mpg)
Fuel Type Diesel
Acceleration 0 – 100 km/h 19.9 sec
Acceleration 0 – 62 mph 19.9 sec
Acceleration 0 – 60 mph 18.9 sec
Maximum speed 148 km/h (91.96 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 gears, manual 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 remains a highly regarded vehicle among enthusiasts, celebrated for its durability, comfort, and classic design. Its robust engineering and relatively simple mechanics make it a rewarding vehicle to own and maintain, ensuring its continued presence on roads around the world.

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