The Mercedes-Benz S123 250 T, produced between September 1979 and August 1982, represents a significant iteration within the W123 series, specifically the T-Modell (estate/station wagon) body style. This variant occupied a mid-range position in the 123 lineup, offering a balance between performance, practicality, and luxury. It was positioned above the smaller displacement models like the 200 T and 230 T, but below the more powerful and expensive 280 TE. The S123 chassis, internally designated as the 123 series, was renowned for its robust engineering and build quality, establishing a benchmark for family vehicles of its era. The 250 T combined a 2.5-liter inline-six engine with a four-speed automatic transmission, catering to buyers seeking a comfortable and refined driving experience.
Powertrain & Engine Architecture
The heart of the S123 250 T is the M 123 V 25 engine, a 2.5-liter (2525 cc) inline-six cylinder gasoline engine. This engine, bearing the code 123.921, is a naturally aspirated powerplant featuring a single overhead camshaft (SOHC) valvetrain with two valves per cylinder. The M123 engine family was known for its smoothness and durability. Fuel delivery is managed by a Bosch K-Jetronic multi-port manifold injection system, a sophisticated system for its time that contributed to improved fuel efficiency and reduced emissions compared to carbureted engines. The engine produces 140 horsepower at 5500 rpm and 200 Nm (147.51 lb-ft) of torque at 3500 rpm. The compression ratio is 9:1. Engine oil capacity is 7.5 liters (7.93 US quarts / 6.6 UK quarts), and the recommended coolant capacity is 10 liters (10.57 US quarts / 8.8 UK quarts).
The engine is longitudinally mounted in the front of the vehicle. Power is transmitted to the rear wheels via a four-speed automatic transmission. While the specific automatic transmission model isn’t widely documented, it was a robust unit designed to handle the engine’s torque output. It featured a torque converter for smooth launches and gear changes. The transmission’s gear ratios were optimized for both comfortable cruising and reasonable acceleration, though it wasn’t designed for particularly sporty performance.
Engine Specifications (M 123 V 25)
- Displacement: 2525 cm³ (154.08 cu. in.)
- Cylinder Bore: 86 mm (3.39 in.)
- Piston Stroke: 72.45 mm (2.85 in.)
- Compression Ratio: 9:1
- Valves per Cylinder: 2
- Fuel Injection: Multi-port manifold injection (Bosch K-Jetronic)
Driving Characteristics
The S123 250 T with the automatic transmission delivers a comfortable and refined driving experience. Acceleration from 0 to 100 km/h (0-62 mph) takes approximately 12.9 seconds, while 0-60 mph is achieved in around 12.3 seconds. The top speed is rated at 180 km/h (111.85 mph). Compared to the manual transmission versions of the 250, the automatic variant sacrifices some responsiveness. The automatic transmission, while providing convenience, introduces a slight power loss and a less direct connection to the engine. The gear ratios are geared towards fuel efficiency and smooth cruising, rather than rapid acceleration. The weight-to-power ratio of 10.8 kg/Hp and weight-to-torque ratio of 7.6 kg/Nm reflect the car’s substantial weight and moderate power output. The engine provides adequate power for highway driving and overtaking, but it doesn’t offer the spirited performance of the larger 280 TE models.
Equipment & Trim Levels
The S123 250 T came reasonably well-equipped as standard, reflecting Mercedes-Benz’s commitment to providing a premium experience. Standard features typically included power steering, front disc brakes, cloth upholstery, and a comprehensive instrument panel. The interior was characterized by its functional design and high-quality materials. Optional extras were plentiful, allowing buyers to customize their vehicles. These included leather upholstery, air conditioning, a sunroof, and upgraded audio systems. The T-Modell’s defining feature, of course, was its spacious cargo area, accessible through a large rear tailgate. The rear seats could be folded down to further increase cargo capacity. Trim levels were relatively simple, with options primarily revolving around the addition of the aforementioned optional extras.
Chassis & Braking
The S123 250 T utilizes a robust chassis designed for comfort and stability. The front suspension employs a double wishbone setup, while the rear suspension features a trailing arm design. This configuration provides a comfortable ride and good handling characteristics. Braking is provided by disc brakes on all four wheels, offering reliable stopping power. The steering system is a cone worm with recirculation balls, providing a relatively direct steering feel, although it requires more effort than modern rack-and-pinion systems. The standard tire size is 195/70 R14, mounted on 6J x 14 inch wheel rims. The car’s substantial weight (1510 kg / 3328.98 lbs kerb weight) necessitates a robust braking system and suspension setup.
Market Reception & Comparison
The S123 250 T was generally well-received by automotive critics. It was praised for its build quality, comfortable ride, and spacious interior. However, some critics noted that the automatic transmission dulled the driving experience compared to the manual versions. Fuel economy was considered reasonable for the time, with urban consumption around 14.5 l/100 km (16.2 US mpg / 19.5 UK mpg) and extra-urban consumption around 9.5 l/100 km (24.8 US mpg / 29.7 UK mpg). Compared to the 230 T, the 250 T offered a noticeable performance improvement. Compared to the 280 TE, the 250 T was more affordable and offered slightly better fuel economy, but lacked the 280’s extra power and prestige. Reliability was a strong point for the S123 series, and the 250 T is generally considered a durable and dependable vehicle.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | W123 |
| Generation | S123 |
| Type | 250 T (140 Hp) Automatic |
| Start of production | September, 1979 |
| End of production | August, 1982 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Station wagon (estate) |
| Seats | 5 |
| Doors | 5 |
| Fuel consumption (urban) | 14.5 l/100 km (16.2 US mpg / 19.5 UK mpg) |
| Fuel consumption (extra urban) | 9.5 l/100 km (24.8 US mpg / 29.7 UK mpg) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 12.9 sec |
| Acceleration 0 – 62 mph | 12.9 sec |
| Acceleration 0 – 60 mph | 12.3 sec |
| Maximum speed | 180 km/h (111.85 mph) |
| Weight-to-power ratio | 10.8 kg/Hp |
| Weight-to-torque ratio | 7.6 kg/Nm |
| Power | 140 Hp @ 5500 rpm |
| Torque | 200 Nm @ 3500 rpm (147.51 lb.-ft. @ 3500 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | M 123 V 25 / 123.921 |
| 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 | 9:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| 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 | 1510 kg (3328.98 lbs.) |
| Max. weight | 2130 kg (4695.85 lbs.) |
| Max load | 620 kg (1366.87 lbs.) |
| Fuel tank capacity | 70 l (18.49 US gal | 15.4 UK gal) |
| Length | 4725 mm (186.02 in.) |
| Width | 1786 mm (70.31 in.) |
| Height | 1470 mm (57.87 in.) |
| Wheelbase | 2795 mm (110.04 in.) |
| Front track | 1488 mm (58.58 in.) |
| Rear track | 1453 mm (57.2 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 |
| Power steering | Hydraulic Steering |
| Tires size | 195/70 R14 |
| Wheel rims size | 6J x 14 |
Legacy
The S123 250 T, like other W123 models, has earned a reputation for exceptional longevity and reliability. The M123 engine, when properly maintained, is capable of accumulating very high mileage. Today, these vehicles are sought after by enthusiasts and collectors, particularly those who appreciate classic Mercedes-Benz engineering. While finding parts can sometimes be a challenge, a robust aftermarket and dedicated community support the preservation of these cars. The automatic transmission, while not as desirable to some as the manual, remains a reliable unit when serviced regularly. The S123 250 T represents a high point in Mercedes-Benz’s commitment to building durable, comfortable, and stylish vehicles, and continues to be a rewarding classic car ownership experience.
