The Mercedes-Benz 420 SE, part of the W126 S-Class range produced from September 1987 to December 1991, represented a significant evolution of the flagship sedan. This facelifted version of the W126, introduced in 1985, solidified the S-Class’s reputation for luxury, engineering, and safety. The 420 SE specifically occupied a middle-ground position within the lineup, offering a compelling blend of performance and refinement, positioned above the 260 SE and 300 SE but below the range-topping 560 SE. It was a key model for Mercedes-Benz in North America and Europe, appealing to buyers seeking a sophisticated and powerful luxury vehicle.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | S-class |
| Generation | S-class SE (W126, facelift 1985) |
| Type (Engine) | 420 SE V8 (231 Hp) Automatic |
| Start of production | September, 1987 |
| End of production | December, 1991 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 5 |
| Doors | 4 |
| Fuel consumption (urban) | 15.1 l/100 km (15.6 US mpg, 18.7 UK mpg, 6.6 km/l) |
| Fuel consumption (extra urban) | 8.7 l/100 km (27 US mpg, 32.5 UK mpg, 11.5 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 8.2 sec |
| Acceleration 0 – 62 mph | 8.2 sec |
| Acceleration 0 – 60 mph | 7.8 sec |
| Maximum speed | 222 km/h (137.94 mph) |
| Weight-to-power ratio | 7.1 kg/Hp, 140.9 Hp/tonne |
| Weight-to-torque ratio | 4.9 kg/Nm, 204.3 Nm/tonne |
| Power | 231 Hp @ 5400 rpm |
| Power per litre | 55.1 Hp/l |
| Torque | 335 Nm @ 4000 rpm (247.08 lb.-ft. @ 4000 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | M 116 E 42 / 116.965 |
| Engine displacement | 4196 cm3 (256.06 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 92 mm (3.62 in.) |
| Piston Stroke | 78.9 mm (3.11 in.) |
| Compression ratio | 10:1 |
| Number of valves per cylinder | 2 |
| Fuel injection system | Multi-port manifold injection |
| Engine aspiration | Naturally aspirated engine |
| Valvetrain | SOHC |
| Engine oil capacity | 8 l (8.45 US qt | 7.04 UK qt) |
| Coolant | 12.5 l (13.21 US qt | 11 UK qt) |
| Kerb Weight | 1640 kg (3615.58 lbs.) |
| Max. weight | 2160 kg (4761.98 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 |
| Assisting systems | ABS (Anti-lock braking system) |
| 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 420 SE is the M116 E 42 engine, a 4.2-liter naturally aspirated V8. This engine, a cornerstone of Mercedes-Benz’s engineering prowess, featured a cast-iron block and aluminum cylinder heads. It employed a single overhead camshaft (SOHC) design with two valves per cylinder. Fuel delivery was managed by a Bosch K-Jetronic multi-port fuel injection system, known for its reliability and precise metering. The engine produced 231 horsepower at 5400 rpm and 335 Nm (247 lb-ft) of torque at 4000 rpm. Paired with the M116 was a four-speed automatic transmission, designed for smooth and refined gear changes. This transmission was a torque converter type, prioritizing comfort over outright performance.
Driving Characteristics
The 420 SE, with its automatic transmission, offered a distinctly different driving experience compared to its manual-transmission siblings or the higher-output 560 SE. While not as overtly sporty, the 420 SE provided ample power for comfortable highway cruising and effortless acceleration. The automatic transmission, while smooth, did result in some power loss compared to a manual, and gear ratios were optimized for relaxed driving rather than aggressive performance. The 0-60 mph time of around 7.8 seconds was respectable for the era, but the focus was more on providing a luxurious and refined experience. The engine’s torque delivery was smooth and linear, making it easy to modulate power in various driving situations.
Equipment & Trim Levels
The 420 SE came standard with a comprehensive list of features befitting its luxury status. These included power windows, power locks, a sunroof, leather upholstery, and climate control. Wood trim adorned the interior, adding to the sense of opulence. Optional extras included a premium sound system, heated seats, and a self-leveling suspension system. The interior layout was classic Mercedes-Benz, emphasizing functionality and understated elegance. The dashboard featured analog gauges and a straightforward control layout.
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 420 SE was equipped with ventilated disc brakes at the front and solid discs at the rear. An Anti-lock Braking System (ABS) was standard, enhancing safety and control during hard braking. The steering was a recirculating ball system with hydraulic power assistance, providing a comfortable and precise steering feel.
Market Reception & Comparison
The 420 SE was generally well-received by automotive critics. It was praised for its comfortable ride, refined interior, and powerful engine. However, some critics noted that the automatic transmission dulled the driving experience compared to the manual versions. Fuel economy, while acceptable for a V8 of this size, was not a strong point, averaging around 15.1 l/100 km (15.6 US mpg) in urban driving. Compared to the 300 SE, the 420 SE offered significantly more power and a more luxurious experience. Compared to the 560 SE, it provided a balance between performance and cost, making it a more accessible option for buyers seeking a top-of-the-line S-Class.
Legacy
The M116 engine, found in the 420 SE, is known for its durability and longevity. With proper maintenance, these engines can reliably exceed 200,000 miles. The W126 S-Class, as a whole, is considered a classic Mercedes-Benz, and well-maintained examples are highly sought after by collectors and enthusiasts. The 420 SE, in particular, represents a sweet spot in the lineup, offering a compelling combination of performance, luxury, and reliability. In the used car market today, the 420 SE commands a premium due to its desirable engine and overall condition. Finding one in pristine condition is becoming increasingly rare, making it a valuable piece of automotive history.
