The Mercedes-Benz W123 represents a pivotal era for the German automaker, produced between July 1975 and September 1979. This series, succeeding the W114 and W115, established a new benchmark for mid-size luxury vehicles, renowned for its engineering robustness, refined design, and commitment to passenger safety. The W123 was not initially a major seller in the United States due to stringent American safety and emissions regulations, but it gained a strong following among enthusiasts who appreciated its build quality and classic Mercedes-Benz character. The 250 model, equipped with a 2.5-liter inline-six engine and automatic transmission, was a popular choice within the W123 range, offering a balance of performance and comfort.
The Mercedes-Benz W123 250: A Legacy of Engineering
The W123 series was a significant departure from its predecessors, incorporating advancements in safety, comfort, and aerodynamics. It was available in sedan (saloon), coupe, and estate (wagon) body styles, catering to a diverse range of customer needs. The 250 model, specifically, was positioned as a premium offering within the lineup, appealing to buyers seeking a sophisticated and reliable vehicle. The W123’s design language, characterized by clean lines and a relatively understated elegance, has aged remarkably well, contributing to its enduring appeal among collectors and enthusiasts today.
Engine & Performance
The heart of the W123 250 is its 2.5-liter (2525 cm3 or 154.08 cu. in.) inline-six cylinder engine, designated M 123 V 25 / 123.920. This naturally aspirated engine produces 129 horsepower at 5500 rpm and 196 Nm (144.56 lb.-ft.) of torque at 3500 rpm. Power per liter is rated at 51.1 Hp/l. The engine features a single overhead camshaft (SOHC) valvetrain and utilizes a carburetor fuel injection system, typical for the era. Power is delivered to the rear wheels via a four-speed automatic transmission. Acceleration from 0 to 100 km/h (0-62 mph) takes 12.2 seconds, while 0 to 60 mph is achieved in approximately 11.6 seconds. The W123 250 boasts a top speed of 180 km/h (111.85 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 seating capacity of five passengers. Its body is constructed with a focus on durability and passenger protection. The exterior design is characterized by a relatively boxy silhouette, typical of 1970s automotive styling, but with a refined and elegant aesthetic. Inside, the W123 250 offers a comfortable and well-appointed cabin, featuring high-quality materials and a focus on ergonomics. Safety features, while not as comprehensive as those found in modern vehicles, were advanced for the time and included crumple zones, reinforced passenger cell construction, and disc brakes on all four wheels. The vehicle’s suspension system utilizes a double wishbone setup at the front and a trailing arm configuration at the rear, providing a comfortable ride and stable handling. The steering system employs a cone worm with recirculation balls. Wheel rims are 5.5J x 14 inches on both the front and rear axles.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | W123 |
| Generation | W123 |
| Type (Engine) | 250 (129 Hp) Automatic |
| 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 l/100 km (14.7 US mpg, 17.7 UK mpg, 6.3 km/l) |
| Fuel consumption (extra urban) | 10.1 l/100 km (23.3 US mpg, 28 UK mpg, 9.9 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 12.2 sec |
| Acceleration 0 – 62 mph | 12.2 sec |
| Acceleration 0 – 60 mph | 11.6 sec |
| Maximum speed | 180 km/h (111.85 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 engine |
| Valvetrain | SOHC |
| Engine oil capacity | 7.5 l (7.93 US qt | 6.6 UK qt) |
| Coolant | 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) |
| 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 Architecture | Rear wheel drive |
| Number of gears and type of gearbox | 4 gears, automatic transmission |
| Front suspension | Double wishbone |
| Rear suspension | Trailing arm |
| Front brakes | Disc |
| Rear brakes | Disc |
| Steering type | Cone worm with recirculation balls |
The Mercedes-Benz W123 250 remains a highly regarded classic car, celebrated for its build quality, reliability, and timeless design. It represents a significant milestone in the evolution of the Mercedes-Benz brand and continues to be cherished by enthusiasts worldwide.
