The Mercedes-Benz S 400d Long, part of the V222 facelift generation produced from 2017 to 2020, represented a significant offering in the luxury sedan segment. Positioned as a high-performance diesel variant within the long-wheelbase S-Class lineup, it aimed to deliver both refined comfort and substantial power. This model catered to buyers seeking a premium experience with enhanced fuel efficiency compared to gasoline-powered alternatives, particularly in European markets where diesel engines held a strong presence. The “Long” designation indicates an extended wheelbase, providing increased rear passenger legroom – a key feature for chauffeur-driven executives and those prioritizing rear-seat comfort.
Technical Specifications
| Brand | Mercedes-Benz |
| Model | S-class |
| Generation | S-class Long (V222, facelift 2017) |
| Type (Engine) | S 400d (340 Hp) G-TRONIC |
| Start of production | 2017 |
| End of production | 2020 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Sedan |
| Seats | 4 |
| Doors | 4 |
| Fuel consumption at Low speed (WLTP) | 6.4 l/100 km (36.8 US mpg, 44.1 UK mpg, 15.6 km/l) |
| Fuel consumption at very high speed (WLTP) | 7.2 l/100 km (32.7 US mpg, 39.2 UK mpg, 13.9 km/l) |
| CO2 emissions (WLTP) | 268-190 g/km |
| Fuel consumption (economy) – urban | 6.4-6.5 l/100 km (36.8 – 36.2 US mpg, 44.1 – 43.5 UK mpg, 15.6 – 15.4 km/l) |
| Fuel consumption (economy) – extra urban | 4.5-4.7 l/100 km (52.3 – 50 US mpg, 62.8 – 60.1 UK mpg, 22.2 – 21.3 km/l) |
| Fuel consumption (economy) – combined | 5.2-5.4 l/100 km (45.2 – 43.6 US mpg, 54.3 – 52.3 UK mpg, 19.2 – 18.5 km/l) |
| CO2 emissions | 135-139 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 5.4 sec |
| Acceleration 0 – 62 mph | 5.4 sec |
| Acceleration 0 – 60 mph | 5.1 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Emission standard | Euro 6 |
| Weight-to-power ratio | 5.7 kg/Hp, 174.4 Hp/tonne |
| Weight-to-torque ratio | 2.8 kg/Nm, 359 Nm/tonne |
| Power | 340 Hp @ 3600-4400 rpm |
| Power per litre | 116.2 Hp/l |
| Torque | 700 Nm @ 1200-3200 rpm (516.29 lb.-ft. @ 1200-3200 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | OM 656.929 |
| Engine displacement | 2925 cm3 (178.49 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Compression ratio | 15.5:1 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Turbocharger, Intercooler |
| Engine oil capacity | 8.5 l (8.98 US qt | 7.48 UK qt) |
| Coolant | 13 l (13.74 US qt | 11.44 UK qt) |
| Kerb Weight | 1950 kg (4299.01 lbs.) |
| Max. weight | 2740 kg (6040.67 lbs.) |
| Max load | 790 kg (1741.65 lbs.) |
| Trunk (boot) space – minimum | 510 l (18.01 cu. ft.) |
| Fuel tank capacity | 70 l (18.49 US gal | 15.4 UK gal) |
| Max. roof load | 100 kg (220.46 lbs.) |
| Permitted trailer load with brakes (12%) | 2100 kg (4629.71 lbs.) |
| Permitted trailer load without brakes | 750 kg (1653.47 lbs.) |
| Length | 5271 mm (207.52 in.) |
| Width | 1905 mm (75 in.) |
| Width including mirrors | 2130 mm (83.86 in.) |
| Height | 1496 mm (58.9 in.) |
| Wheelbase | 3165 mm (124.61 in.) |
| Front track | 1630 mm (64.17 in.) |
| Rear (Back) track | 1643 mm (64.69 in.) |
| Front overhang | 898 mm (35.35 in.) |
| Rear overhang | 1208 mm (47.56 in.) |
| Drag coefficient (Cd) | 0.24 |
| Minimum turning circle (turning diameter) | 12.3 m (40.35 ft.) |
| 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 | 9 gears, automatic transmission G-TRONIC |
| Front suspension | Independent multi-link suspension |
| Rear suspension | Independent multi-link suspension |
| Front brakes | Ventilated discs |
| Rear brakes | Ventilated discs |
| Assisting systems | ABS (Anti-lock braking system) |
| Steering type | Steering rack and pinion |
| Power steering | Electric Steering |
| Tires size | 245/50 R18 |
| Wheel rims size | 18 |
INTRODUCTION
The S 400d Long, introduced as part of the V222 facelift in 2017, built upon the already highly regarded S-Class platform. The facelift brought subtle but significant updates to the exterior styling, interior technology, and engine options. The S 400d specifically aimed to provide a compelling alternative to the gasoline-powered S 500, offering comparable performance with improved fuel economy and a broader torque curve. Its positioning within the S-Class range was as a premium diesel offering, appealing to buyers who prioritized long-distance comfort, refinement, and efficiency. The extended wheelbase (“Long” variant) further emphasized the car’s luxury credentials, making it a popular choice for executive transport.
Powertrain & Engine Architecture
At the heart of the S 400d Long lies the OM 656.929, a 2.9-liter inline-six cylinder diesel engine. This engine represented a significant advancement in Mercedes-Benz’s diesel technology, featuring a sophisticated commonrail direct injection system operating at extremely high pressures. The engine utilizes a two-stage turbocharging system with a variable geometry turbine, enhancing both low-end responsiveness and high-end power delivery. The high compression ratio of 15.5:1 contributes to thermal efficiency. Paired with the engine is the 9G-TRONIC nine-speed automatic transmission, known for its smooth shifts and wide gear ratio spread. This transmission is designed to optimize fuel economy and provide seamless acceleration. The G-TRONIC transmission features adaptive shift programs that adjust to the driver’s style and the road conditions.
Driving Characteristics
The S 400d Long delivers a remarkably refined driving experience. The inline-six diesel engine provides a substantial 700 Nm (516 lb-ft) of torque available from a low 1200 rpm, resulting in effortless acceleration and strong pulling power. The 0-60 mph sprint takes approximately 5.1 seconds, making it surprisingly quick for a large luxury sedan. The 9G-TRONIC transmission contributes to this performance by keeping the engine within its optimal power band. Compared to the S 500, the S 400d offers a slightly different character. While the S 500 prioritizes outright power and a more sporty feel, the S 400d emphasizes relaxed cruising and effortless overtaking. The long wheelbase contributes to a smooth and stable ride, absorbing bumps and imperfections in the road with ease.
Equipment & Trim Levels
The S 400d Long typically came generously equipped, reflecting its position as a flagship luxury sedan. Standard features included leather upholstery, heated and ventilated front seats with massage functions, a premium Burmester surround sound system, a large infotainment display with navigation, and a comprehensive suite of driver-assistance systems such as adaptive cruise control, lane-keeping assist, and automatic emergency braking. Optional extras included rear-seat entertainment systems, a panoramic sunroof, and various customization options for interior trim and exterior paint. The interior design focused on creating a luxurious and comfortable environment, with high-quality materials and meticulous attention to detail.
Chassis & Braking
The S 400d Long features an independent multi-link suspension at both the front and rear axles, providing a comfortable and controlled ride. The suspension is electronically controlled, adapting to road conditions and driving style. Ventilated disc brakes are fitted on all four wheels, providing ample stopping power. The car is equipped with ABS (Anti-lock Braking System), Electronic Stability Program (ESP), and other advanced safety features. The steering is a rack-and-pinion system with electric power assistance, offering precise and responsive handling.
Market Reception & Comparison
The S 400d Long was generally well-received by automotive critics. It was praised for its refined engine, comfortable ride, luxurious interior, and impressive fuel economy. Compared to the S 500, the S 400d offered a more economical option without sacrificing significant performance. However, some critics noted that the diesel engine lacked the outright excitement of the gasoline-powered S 500. In terms of reliability, the OM 656 engine proved to be robust and dependable, although diesel particulate filter (DPF) maintenance required attention, particularly for drivers who primarily undertake short journeys.
Legacy
The Mercedes-Benz S 400d Long (V222 facelift) remains a desirable used car option today. Its combination of luxury, performance, and fuel efficiency continues to appeal to buyers seeking a high-end sedan. The OM 656 engine has established a reputation for reliability, and the 9G-TRONIC transmission is known for its smooth operation. While newer S-Class models offer even more advanced technology, the V222 facelift S 400d Long represents a sweet spot in terms of value and refinement, offering a luxurious and capable driving experience at a more accessible price point.
