The Mercedes-Benz S 450, part of the W222 facelift generation produced from 2017 to 2020, represented a significant evolution of the flagship S-Class sedan. This variant occupied a middle ground within the W222 lineup, positioned above the S 350d and S 400d diesel models, but below the more performance-oriented S 560 and AMG variants. The S 450 distinguished itself through the integration of Mercedes-Benz’s EQ Boost mild-hybrid system, enhancing both fuel efficiency and driving refinement. It was designed to appeal to buyers seeking a luxurious and technologically advanced sedan with a balance of performance and economy.
Powertrain & Engine Architecture
At the heart of the S 450 lies the M 256 3.0-liter inline-six cylinder engine, a groundbreaking design for Mercedes-Benz. This engine, designated M 256.930, marked a departure from the traditional V6 configuration, offering improved efficiency and smoothness. It features direct fuel injection, a twin-scroll turbocharger with intercooling, and a sophisticated four-valve-per-cylinder DOHC valvetrain. The engine produces 367 horsepower at 5500-6100 rpm and 500 Nm (368.78 lb-ft) of torque between 1600-4000 rpm, resulting in a power-to-liter ratio of 122.4 hp/l.
The key innovation in the S 450’s powertrain is the EQ Boost system. This 48-volt mild-hybrid system incorporates a 22 hp electric motor integrated between the engine and the 9G-TRONIC automatic transmission. The electric motor provides supplemental power during acceleration, smoothing out gear changes and reducing turbo lag. It also enables features like ‘glide sailing’ where the engine shuts off during coasting to conserve fuel. The system utilizes a 0.9 kWh lithium-ion battery. The 9G-TRONIC automatic transmission, with its nine forward gears, is optimized for both fuel efficiency and responsive performance. Gear ratios are carefully calibrated to maximize the engine’s torque output and provide smooth, seamless shifts.
Engine Specifications
The M 256 engine benefits from advanced technologies such as NANOSLIDE cylinder coating, reducing friction and wear. The engine’s layout is longitudinal, positioned at the front of the vehicle. It boasts a compression ratio of 10.5:1, a cylinder bore of 83 mm (3.27 in), and a piston stroke of 92.4 mm (3.64 in). Engine oil capacity is 8.5 liters (8.98 US qt | 7.48 UK qt), and it requires a specific oil specification as outlined by Mercedes-Benz.
Driving Characteristics
The S 450 delivers a refined and effortless driving experience. The combination of the inline-six engine and the EQ Boost system provides ample power for both city driving and highway cruising. Acceleration from 0 to 100 km/h (0-62 mph) takes approximately 4.9 seconds, and 0-60 mph is achieved in around 4.7 seconds. The 9G-TRONIC transmission contributes to smooth and almost imperceptible gear changes, enhancing the overall comfort. The EQ Boost system provides an immediate boost of torque, making overtaking maneuvers feel confident and responsive. Compared to the S 350d, the S 450 offers noticeably quicker acceleration and a more spirited driving experience. While not as overtly sporty as the S 560, the S 450 provides a satisfying balance of performance and luxury.
The electronically limited top speed of 250 km/h (155.34 mph) ensures ample performance for most driving situations. The car’s weight distribution and sophisticated suspension system contribute to stable and predictable handling. The steering is precise and well-weighted, providing a connected feel to the road.
Equipment & Trim Levels
The S 450 came standard with a comprehensive array of luxury features. Interior upholstery typically consisted of high-quality leather, with a wide range of color options available. The dashboard featured a dual 12.3-inch display screen, showcasing the instrument cluster and infotainment system. Standard equipment included Mercedes-Benz’s COMAND infotainment system, navigation, premium sound system, ambient lighting, and a panoramic sunroof.
Optional extras were plentiful, allowing buyers to personalize their S 450 to their exact preferences. These included features such as massaging seats, rear-seat entertainment, a Burmester surround sound system, advanced driver-assistance systems (like Distronic Plus adaptive cruise control and lane-keeping assist), and various interior trim options. The S 450 was often specified with the Premium Package, which bundled many of the most desirable options together.
Chassis & Braking
The S 450 utilizes an independent multi-link suspension system 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. The car is equipped with ventilated disc brakes on all four wheels, providing ample stopping power. Anti-lock braking system (ABS) is standard, along with electronic stability control. The S 450’s steering system is a rack-and-pinion type with electric power steering. Standard tire size is 245/50 R18, mounted on 8J x 18 inch wheel rims.
Market Reception & Comparison
The S 450 was generally well-received by automotive critics. It was praised for its refined driving experience, luxurious interior, and advanced technology. The EQ Boost system was lauded for its ability to improve fuel efficiency without compromising performance. Fuel consumption figures, according to WLTP testing, ranged from 7.0-7.3 l/100 km (33.6 – 32.2 US mpg, 40.4 – 38.7 UK mpg). CO2 emissions were rated between 159-167 g/km. Compared to the S 560, the S 450 offered a more fuel-efficient alternative, while still providing a luxurious and comfortable driving experience. The S 450’s mild-hybrid system also gave it a slight edge in terms of emissions compared to the non-hybrid S 560.
Technical Specifications
| Body type | Sedan, 4 Doors, 4-5 Seats |
| Fuel economy (combined) | 7.0-7.3 l/100 km (33.6 – 32.2 US mpg, 40.4 – 38.7 UK mpg) |
| CO2 emissions | 192-208 g/km |
| Maximum speed | 250 km/h (155.34 mph) |
| Acceleration 0-100 km/h | 4.9 sec |
| Engine size | 3.0 l (2999 cm3 / 183.01 cu. in.) |
| Number of cylinders | 6, Inline |
| Power | 367 Hp @ 5500-6100 rpm |
| Torque | 500 Nm @ 1600-4000 rpm (368.78 lb-ft) |
| Drivetrain | All wheel drive (4×4) with 9G-TRONIC automatic transmission |
| Kerb Weight | 1985 kg (4376.18 lbs) |
| Fuel tank capacity | 70 l (18.49 US gal | 15.4 UK gal) |
| Trunk (boot) space | 510 l (18.01 cu. ft) |
Legacy
The S 450, with its M 256 engine and EQ Boost technology, represented a forward-thinking approach to luxury motoring. The M 256 engine has proven to be a reliable and durable powerplant, and the EQ Boost system has generally experienced few issues. On the used car market, the S 450 offers a compelling value proposition, providing a high level of luxury and technology at a more accessible price point than the higher-performance S 560 or AMG models. Regular maintenance, including oil changes and adherence to Mercedes-Benz’s recommended service intervals, is crucial for ensuring the long-term reliability of this powertrain. The S 450 remains a desirable and technologically advanced luxury sedan, offering a refined and comfortable driving experience for years to come.
