The Mercedes-Benz W123 is a compact executive car produced from 1976 to 1985. Representing the successor to the W114 model line, the W123 is renowned for its engineering, build quality, and longevity. It established Mercedes-Benz as a dominant force in the mid-size luxury segment. The 250 model, produced from July 1975 to September 1979, was a key variant within the W123 range, offering a balance of performance and fuel efficiency. This article details the specifications and characteristics of the W123 250, a vehicle that remains highly sought after by enthusiasts today.
The Mercedes-Benz W123 250: A Legacy of Engineering
The W123 was a pivotal model for Mercedes-Benz, introducing numerous advancements in safety and comfort. It was available in sedan, coupe, and estate (wagon) body styles, catering to a wide range of customer needs. The 250 model, powered by a 2.5-liter inline-six engine, was positioned as a premium offering within the lineup. While not initially sold in large numbers in the United States (US market introduction came later in the W123 lifecycle), the W123 gained a strong reputation for reliability and durability, becoming a popular import and a symbol of German automotive engineering.
Engine & Performance
The heart of the W123 250 is its M 123 V 25 inline-six cylinder engine. This 2.5-liter (2525 cm3 or 154.08 cu. in.) naturally aspirated engine produces 129 horsepower at 5500 rpm and 196 Nm (144.56 lb.-ft.) of torque at 3500 rpm. The engine features a single overhead camshaft (SOHC) valvetrain with two valves per cylinder and utilizes a carburetor fuel injection system. This configuration delivers a power-to-liter ratio of 51.1 hp/l. Power is delivered to the rear wheels via a 4-speed manual transmission. Acceleration from 0 to 100 km/h (0-62 mph) takes 11.3 seconds, while 0 to 60 mph is achieved in approximately 10.7 seconds. The W123 250 boasts a maximum speed of 185 km/h (114.95 mph). The weight-to-power ratio is 10.9 kg/Hp, and the weight-to-torque ratio is 7.2 kg/Nm.
Design & Features
The W123 250 is a four-door sedan with a classic, understated design. Its body is characterized by clean lines, a relatively upright stance, and a focus on practicality. The interior is well-appointed, offering comfortable seating for five passengers. Safety was a key consideration in the W123’s design, featuring crumple zones in the front and rear, and a reinforced passenger safety cell. Disc brakes are fitted on all four wheels, providing reliable stopping power. The suspension utilizes a double wishbone setup at the front and a trailing arm configuration at the rear, offering a comfortable ride and predictable handling. The steering system employs a cone worm with recirculation balls. The vehicle’s dimensions are: length 4725 mm (186.02 in), width 1786 mm (70.31 in), and height 1438 mm (56.61 in), with a wheelbase of 2795 mm (110.04 in). The front and rear track widths are 1488 mm (58.58 in) and 1446 mm (56.93 in) respectively.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | W123 |
| Generation | W123 |
| Type (Engine) | 250 (129 Hp) |
| Start of production | July, 1975 |
| End of production | September, 1979 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 16.4 l/100 km (14.3 US mpg / 17.2 UK mpg / 6.1 km/l) |
| Fuel consumption (extra urban) | 9.8 l/100 km (24 US mpg / 28.8 UK mpg / 10.2 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 11.3 sec |
| Acceleration 0 – 62 mph | 11.3 sec |
| Acceleration 0 – 60 mph | 10.7 sec |
| Maximum speed | 185 km/h (114.95 mph) |
| Weight-to-power ratio | 10.9 kg/Hp |
| Weight-to-torque ratio | 7.2 kg/Nm |
| Power | 129 Hp @ 5500 rpm |
| Power per litre | 51.1 Hp/l |
| Torque | 196 Nm @ 3500 rpm (144.56 lb.-ft. @ 3500 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | M 123 V 25 / 123.920 |
| Engine displacement | 2525 cm3 (154.08 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 86 mm (3.39 in.) |
| Piston Stroke | 72.45 mm (2.85 in.) |
| Compression ratio | 8.7:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Carburettor |
| Engine aspiration | Naturally aspirated |
| Valvetrain | SOHC |
| Engine oil capacity | 7.5 l (7.93 US qt | 6.6 UK qt) |
| Coolant capacity | 10 l (10.57 US qt | 8.8 UK qt) |
| Kerb Weight | 1410 kg (3108.52 lbs.) |
| Max. weight | 1930 kg (4254.92 lbs.) |
| Max load | 520 kg (1146.4 lbs.) |
| Fuel tank capacity | 80 l (21.13 US gal | 17.6 UK gal) |
| Front wheel rims size | 5.5J x 14 |
| Rear wheel rims size | 5.5J x 14 |
| Number of gears and type of gearbox | 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 |
| Drivetrain Architecture | Rear wheel drive |
The Mercedes-Benz W123 250 represents a high point in German automotive engineering. Its combination of robust construction, refined performance, and understated elegance has ensured its enduring appeal among collectors and enthusiasts. The W123’s legacy continues to influence automotive design and engineering standards today.
