The Mercedes-Benz W124, produced from 1985 to 1996, represented a significant leap forward in engineering and design for the German automaker. The facelifted version introduced in 1989, and specifically the 300 D CAT model, refined the already successful W124 platform. This model, powered by a 3.0-liter diesel engine, was primarily aimed at the European market, where diesel sedans were highly favored for their fuel efficiency and durability. While not widely sold in the United States due to emissions regulations and consumer preference for larger engines, the W124 established Mercedes-Benz as a benchmark for quality and reliability in the mid-size luxury segment.
Mercedes-Benz W124 (Facelift 1989) 300 D CAT
The W124 series was designed as a successor to the W201 (190E) and W123 models, offering a more modern and sophisticated package. The 1989 facelift brought subtle but important changes to the exterior, including revised headlights, taillights, and front and rear bumpers. The 300 D CAT, equipped with a catalytic converter (hence the “CAT” designation), was a key variant, offering a balance of performance and economy. It was positioned as a premium sedan, competing with models like the BMW 5 Series and Audi 100.
Engine & Performance
The heart of the 300 D CAT is its OM 603 D 30 inline-six cylinder diesel engine, displacing 2,996 cubic centimeters (182.83 cubic inches). This naturally aspirated engine produces 110 horsepower at 4,600 rpm and 191 Newton-meters (140.87 lb.-ft.) of torque between 2,800 and 3,050 rpm. While the horsepower figure might seem modest by modern standards, the engine’s torque delivery provides strong and usable power for everyday driving. The engine utilizes precombustion chamber injection, a technology common in Mercedes-Benz diesels of the era, for efficient combustion and reduced emissions. Acceleration from 0 to 100 km/h (0-62 mph) takes 13.7 seconds, and it achieves a top speed of 190 km/h (118.06 mph). The fuel economy is a strong point, achieving approximately 9.8 liters per 100 kilometers (24 US mpg) in urban conditions and 5.4 liters per 100 kilometers (43.6 US mpg) on the open road. The engine’s weight-to-power ratio is 13.1 kg/Hp, and the weight-to-torque ratio is 7.5 kg/Nm.
Design & Features
The W124 300 D CAT is a four-door sedan with a classic, understated Mercedes-Benz design. Its body is characterized by clean lines, a relatively upright stance, and a focus on practicality. The interior is well-appointed, with comfortable seating for five passengers. Key features included power steering, disc brakes on all four wheels, and an anti-lock braking system (ABS) for enhanced safety. The 1989 facelift brought improvements to interior trim and materials, further enhancing the sense of luxury. The vehicle’s robust construction and attention to detail were hallmarks of Mercedes-Benz engineering. The suspension system, featuring wishbones at the front and an independent multi-link setup at the rear, provided a comfortable and controlled ride. The car’s dimensions are 4,740 mm (186.61 in) in length, 1,740 mm (68.5 in) in width, and 1,428 mm (56.22 in) in height, with a wheelbase of 2,800 mm (110.24 in).
Technical Specifications
| Brand | Mercedes-Benz |
| Model | W124 |
| Generation | W124 (facelift 1989) |
| Type (Engine) | 300 D CAT (110 Hp) |
| Start of production | September, 1989 |
| End of production | July, 1993 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 9.8 l/100 km (24 US mpg) |
| Fuel consumption (extra urban) | 5.4 l/100 km (43.6 US mpg) |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 13.7 sec |
| Acceleration 0 – 62 mph | 13.7 sec |
| Acceleration 0 – 60 mph | 13 sec |
| Maximum speed | 190 km/h (118.06 mph) |
| Weight-to-power ratio | 13.1 kg/Hp |
| Weight-to-torque ratio | 7.5 kg/Nm |
| Power | 110 Hp @ 4600 rpm |
| Torque | 191 Nm @ 2800-3050 rpm (140.87 lb.-ft.) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | OM 603 D 30 / 603.912 |
| Engine displacement | 2996 cm3 (182.83 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 87 mm (3.43 in.) |
| Piston Stroke | 84 mm (3.31 in.) |
| Compression ratio | 22:1 |
| 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 | 9 l (9.51 US qt | 7.92 UK qt) |
| Kerb Weight | 1440 kg (3174.66 lbs.) |
| Max. weight | 2020 kg (4453.34 lbs.) |
| Max load | 580 kg (1278.68 lbs.) |
| Fuel tank capacity | 70 l (18.49 US gal | 15.4 UK gal) |
| Length | 4740 mm (186.61 in.) |
| Width | 1740 mm (68.5 in.) |
| Height | 1428 mm (56.22 in.) |
| Wheelbase | 2800 mm (110.24 in.) |
| Front track | 1501 mm (59.09 in.) |
| Rear track | 1491 mm (58.7 in.) |
| Drivetrain Architecture | Rear wheel drive |
| Number of gears | 5 gears, manual transmission |
| Front suspension | Wishbone |
| Rear suspension | Independent multi-link suspension |
| Front brakes | Disc |
| Rear brakes | Disc |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Cone worm with recirculation balls |
| Power steering | Hydraulic |
| Tires size | 195/65 R15 |
| Wheel rims size | 6.5J x 15 |
The Mercedes-Benz W124 300 D CAT remains a highly regarded vehicle, celebrated for its build quality, reliability, and comfortable driving experience. Its enduring appeal lies in its ability to provide a refined and practical motoring experience, even decades after its production ended. It represents a high point in Mercedes-Benz engineering and a testament to the brand’s commitment to quality and innovation.
