The Mercedes-Benz 300 SE, part of the W126 S-Class range produced from August 1985 to October 1991, represented a significant evolution of the flagship sedan. This facelifted version of the W126, introduced in 1985, brought subtle but important updates to the already highly regarded S-Class. The 300 SE, equipped with a 3.0-liter inline-six engine and a four-speed automatic transmission, occupied a middle ground in the lineup, offering a balance of performance, luxury, and fuel efficiency. It served as a popular choice for buyers seeking the prestige of the S-Class without the higher price tag of the V8-powered models like the 560 SEL.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | S-class |
| Generation | S-class SE (W126, facelift 1985) |
| Type (Engine) | 300 SE (188 Hp) Automatic |
| Start of production | August, 1985 |
| End of production | October, 1991 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 13.6 l/100 km (17.3 US mpg, 20.8 UK mpg, 7.4 km/l) |
| Fuel consumption (extra urban) | 9.4 l/100 km (25 US mpg, 30.1 UK mpg, 10.6 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 9.1 sec |
| Acceleration 0 – 62 mph | 9.1 sec |
| Acceleration 0 – 60 mph | 8.6 sec |
| Maximum speed | 205 km/h (127.38 mph) |
| Weight-to-power ratio | 8.1 kg/Hp, 123.7 Hp/tonne |
| Weight-to-torque ratio | 5.8 kg/Nm, 171.1 Nm/tonne |
| Power | 188 Hp @ 5700 rpm |
| Power per litre | 63.5 Hp/l |
| Torque | 260 Nm @ 4400 rpm (191.77 lb.-ft. @ 4400 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | M 103 E 30 / 103.981 |
| Engine displacement | 2962 cm3 (180.75 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 88.5 mm (3.48 in.) |
| Piston Stroke | 80.25 mm (3.16 in.) |
| Compression ratio | 9.2:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | SOHC |
| Engine oil capacity | 6 l (6.34 US qt | 5.28 UK qt) |
| Coolant | 8 l (8.45 US qt | 7.04 UK qt) |
| Kerb Weight | 1520 kg (3351.03 lbs.) |
| Max. weight | 2040 kg (4497.43 lbs.) |
| Max load | 520 kg (1146.4 lbs.) |
| Fuel tank capacity | 90 l (23.78 US gal | 19.8 UK gal) |
| Length | 5020 mm (197.64 in.) |
| Width | 1820 mm (71.65 in.) |
| Height | 1437 mm (56.57 in.) |
| Wheelbase | 2930 mm (115.35 in.) |
| Front track | 1555 mm (61.22 in.) |
| Rear (Back) track | 1527 mm (60.12 in.) |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 4 gears, automatic transmission |
| Front suspension | Double wishbone |
| Rear suspension | Trailing arm |
| Front brakes | Ventilated discs |
| Rear brakes | Disc |
| Steering type | Cone worm with recirculation balls |
| Power steering | Hydraulic Steering |
| Tires size | Front wheel tires: 205/65 R15Rear wheel tires: 205/65 R15 |
| Wheel rims size | Front wheel rims: 7J x 15Rear wheel rims: 7J x 15 |
Powertrain & Engine Architecture
The heart of the 300 SE was the M103 E 30 engine, a 2,962 cc (180.75 cu. in.) inline-six cylinder powerplant. This engine featured a cast-iron block and an aluminum cylinder head, employing a single overhead camshaft (SOHC) design with two valves per cylinder. Bosch K-Jetronic fuel injection was utilized, a mechanical system known for its reliability and precise fuel delivery. The M103 was renowned for its smooth operation and relatively high specific output for a naturally aspirated engine of its time. The four-speed automatic transmission, a robust unit developed in-house by Mercedes-Benz, was specifically tuned to complement the engine’s torque curve, providing smooth and comfortable shifts. This transmission lacked the modern overdrive gears found in later automatics, impacting highway fuel economy.
Driving Characteristics
The 300 SE Automatic offered a refined and comfortable driving experience, typical of the S-Class. While not overtly sporty, the 188 horsepower engine provided adequate acceleration, reaching 60 mph in around 8.6 seconds. The automatic transmission, while smooth, did result in some power loss compared to the five-speed manual option available on other 300 SE models. The gear ratios were optimized for relaxed cruising, making it an excellent grand tourer. However, aggressive driving revealed the limitations of the engine’s torque, requiring frequent downshifts to maintain momentum. Compared to the higher-performance 300 SEL 6.3 or the later 400 SE, the 300 SE Automatic prioritized comfort and fuel efficiency over outright speed.
Equipment & Trim Levels
The 300 SE came standard with a generous array of features, reflecting its status as a luxury vehicle. These included power windows, central locking, air conditioning, and a high-quality sound system. The interior was typically upholstered in leather, with wood trim adorning the dashboard and door panels. Optional extras included a sunroof, heated seats, and a more advanced audio system. The 300 SE’s trim level was positioned as a mid-range offering, providing a substantial level of luxury without the expense of the top-of-the-line models.
Chassis & Braking
The W126 S-Class featured a robust chassis with independent suspension all around. The front suspension utilized a double wishbone design, while the rear employed a trailing arm setup. This configuration provided a comfortable ride and good handling characteristics. The 300 SE was equipped with ventilated disc brakes at the front and solid discs at the rear. Power-assisted steering was standard, providing light and precise control. The suspension was tuned for comfort, prioritizing a smooth ride over sharp handling.
Market Reception & Comparison
The 300 SE Automatic was well-received by critics and buyers alike. It was praised for its comfortable ride, refined interior, and reliable powertrain. Fuel economy, while not exceptional, was considered reasonable for a vehicle of its size and class. Compared to the 280 SE, the 300 SE offered a noticeable performance improvement. However, the 400 SE and 560 SEL provided significantly more power, albeit at a higher price point and with increased fuel consumption. The 300 SE struck a balance, appealing to buyers who wanted the prestige of the S-Class without the expense of the larger-engined models.
Legacy
The W126 S-Class, including the 300 SE, is now considered a classic Mercedes-Benz. The M103 engine is known for its durability and longevity, and well-maintained examples can still provide reliable service today. The 300 SE Automatic remains a popular choice among enthusiasts, offering a blend of luxury, comfort, and classic styling. While parts availability can be a concern, the M103 engine is relatively straightforward to maintain, and a dedicated community of owners and specialists exists to support these vehicles. The 300 SE represents a high point in Mercedes-Benz engineering and design, and continues to be appreciated for its timeless appeal.
