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 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 primarily marketed towards executives and those seeking a sophisticated, comfortable, and technologically advanced vehicle. The “SE” designation stood for “Sonderausstattung” – Special Equipment – indicating a higher level of standard features compared to base models.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | S-class |
| Generation | S-class SE (W126, facelift 1985) |
| Type (Engine) | 420 SE V8 CAT (224 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) | 15.4 l/100 km (15.3 US mpg, 18.3 UK mpg, 6.5 km/l) |
| Fuel consumption (extra urban) | 9.1 l/100 km (25.8 US mpg, 31 UK mpg, 11 km/l) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 8.3 sec |
| Acceleration 0 – 62 mph | 8.3 sec |
| Acceleration 0 – 60 mph | 7.9 sec |
| Maximum speed | 220 km/h (136.7 mph) |
| Weight-to-power ratio | 7.3 kg/Hp, 136.6 Hp/tonne |
| Weight-to-torque ratio | 5 kg/Nm, 198.2 Nm/tonne |
| Power | 224 Hp @ 5400 rpm |
| Power per litre | 53.4 Hp/l |
| Torque | 325 Nm @ 4000 rpm (239.71 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 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 was the M116 E 42 engine, a 4.2-liter naturally aspirated V8. This engine, a cornerstone of Mercedes-Benz engineering, 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 handled by a Bosch K-Jetronic multi-port fuel injection system, a sophisticated system for its time, known for its precision and reliability. The catalytic converter (“CAT” in the model designation) was standard, reflecting increasing environmental regulations. The engine produced 224 horsepower at 5400 rpm and 325 Nm (239.71 lb-ft) of torque at 4000 rpm. The engine was longitudinally mounted, driving the rear wheels. Paired with the M116 was a four-speed automatic transmission, providing smooth and refined gear changes. This transmission was designed for comfort rather than outright performance, with relatively conservative gear ratios.
Driving Characteristics
The 420 SE offered a driving experience focused on comfort and effortless cruising. While not a sports sedan, the 4.2-liter V8 provided ample power for confident overtaking and highway merging. Acceleration from 0 to 60 mph took approximately 7.9 seconds, respectable for the late 1980s. The automatic transmission, while smooth, did contribute to a slight reduction in responsiveness compared to the available manual transmission options in other S-Class models. The gear ratios were optimized for fuel efficiency and relaxed driving, rather than aggressive acceleration. The car felt substantial and planted on the road, thanks to its weight and well-tuned suspension.
Equipment & Trim Levels
The 420 SE came standard with a generous array of features, befitting its status as a luxury vehicle. These included power windows, power locks, a sunroof, leather upholstery, climate control, and an AM/FM stereo. The interior was characterized by high-quality materials and meticulous craftsmanship. Optional extras included a premium sound system, heated seats, and a self-leveling suspension system. The wood trim on the dashboard and door panels added to the luxurious ambiance.
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 disc brakes 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 luxurious interior, comfortable ride, and refined engine. However, some critics noted that the automatic transmission could feel somewhat sluggish compared to manual options. Compared to the 260 SE and 300 SE, the 420 SE offered significantly more power and a more luxurious driving experience. Compared to the 560 SE, it provided a balance between performance and fuel economy, making it a more practical choice for some buyers. Fuel economy, while not a priority for S-Class buyers, was reasonable for a V8 engine of this size, averaging around 15.4 l/100 km in urban driving and 9.1 l/100 km on the highway.
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 good balance of performance, luxury, and reliability. Today, finding a pristine 420 SE can be challenging, but those that remain are prized for their timeless design and engineering excellence. Parts availability is generally good, although some specific components may be difficult to source.
