The Mercedes-Benz S 450 4MATIC, produced between 2006 and 2009, was a key variant within the W221 generation of the S-Class. Positioned as a mid-range offering in the lineup, it bridged the gap between the entry-level S 350 and the more powerful S 550 and S 600 models. This model combined a naturally aspirated 4.7-liter V8 engine with a 7G-TRONIC seven-speed automatic transmission and Mercedes-Benz’s 4MATIC all-wheel-drive system, offering a blend of performance, luxury, and all-weather capability. The W221 S-Class represented a significant leap forward in technology and refinement for the brand, and the S 450 4MATIC played a substantial role in its market success.
Powertrain & Engine Architecture
The heart of the S 450 4MATIC is the M273.924 engine, a 4.7-liter (4663 cc) naturally aspirated V8. This engine produces 340 horsepower at 6000 rpm and 460 Nm (339.28 lb-ft) of torque between 2700 and 5000 rpm. The engine features a compression ratio of 10.5:1, four valves per cylinder, and multi-port fuel injection. The engine’s architecture is longitudinal, meaning it’s mounted lengthwise in the engine bay. The M273 engine family was known for its smooth operation and relatively high power output for its displacement. It utilized a three-valve per cylinder design (two intake, one exhaust) and a relatively lightweight construction for improved responsiveness.
The 7G-TRONIC automatic transmission, designated as 722.906, is a seven-speed unit that was a significant advancement over previous Mercedes-Benz automatic transmissions. It offered smoother shifts, improved fuel efficiency, and a wider range of gear ratios. The transmission features a torque converter lock-up clutch that engages in most gears, further enhancing efficiency. The 7G-TRONIC also incorporated a manual shift mode, allowing drivers to select gears sequentially for more control. The 4MATIC all-wheel-drive system distributes power to all four wheels, providing enhanced traction and stability, particularly in adverse weather conditions. The system operates full-time, with a rear-biased distribution for a more traditional driving feel.
Engine Details
The M273 engine benefits from advanced engine management systems, optimizing fuel delivery and ignition timing for maximum performance and efficiency. The engine oil capacity is 8.5 liters (8.98 US quarts / 7.48 UK quarts), and Mercedes-Benz specified particular oil grades to ensure optimal lubrication and longevity. The engine also utilizes a sophisticated cooling system to maintain consistent operating temperatures.
Driving Characteristics
The S 450 4MATIC delivers a refined and comfortable driving experience. Acceleration from 0 to 100 km/h (0-62 mph) takes approximately 5.9 seconds, and 0-60 mph is achieved in around 5.6 seconds. While not as overtly sporty as the higher-powered S 550 or AMG models, the S 450 provides ample power for confident overtaking and highway cruising. The 7G-TRONIC transmission contributes to smooth and seamless gear changes, enhancing the overall driving experience. The 4MATIC system provides a secure and planted feel, particularly on slippery surfaces. Compared to the rear-wheel-drive S 350, the S 450 4MATIC offers noticeably improved traction and stability. The naturally aspirated V8 provides a linear power delivery, making it predictable and easy to modulate.
Equipment & Trim Levels
The S 450 4MATIC came standard with a comprehensive array of luxury features, befitting its position in the S-Class range. Standard equipment typically included leather upholstery, power-adjustable heated and ventilated front seats, a premium sound system, a multi-function steering wheel, automatic climate control, and a sunroof. The interior was characterized by high-quality materials and meticulous craftsmanship. Optional extras included a rear seat entertainment system, massaging seats, a panoramic sunroof, and various driver-assistance features such as Distronic adaptive cruise control and Parktronic parking assist. Trim levels were relatively limited, with most customization occurring through the selection of individual options. Wood trim was a common feature, available in a variety of finishes.
Chassis & Braking
The S 450 4MATIC utilizes an air suspension system on both the front and rear axles, providing a remarkably smooth and comfortable ride. The air suspension automatically adjusts to varying road conditions and load levels, maintaining a consistent ride height and minimizing body roll. The braking system consists of ventilated discs on all four wheels, providing ample stopping power. Anti-lock braking system (ABS) was standard, enhancing safety and control during emergency braking situations. The steering system is a rack-and-pinion setup, offering precise and responsive steering feel. The vehicle rides on 235/55 R17 tires mounted on 17-inch alloy wheels.
Market Reception & Comparison
The S 450 4MATIC was generally well-received by automotive critics, who praised its blend of performance, luxury, and all-weather capability. It was considered a strong value proposition within the S-Class range, offering a significant step up in performance and features compared to the S 350 without the substantial price premium of the S 550 or S 600. Fuel economy was reasonable for a vehicle of its size and performance, with combined fuel consumption figures around 11.6-11.8 l/100 km (20.3-20.6 US mpg). Reliability was generally good, although some owners reported issues with the air suspension system and electronic components. Compared to the S 550, the S 450 offered a more balanced driving experience, with less emphasis on outright performance and more focus on comfort and refinement.
Technical Specifications
| Body Type | Sedan, 4 Doors, 5 Seats |
| Fuel Economy (Combined) | 11.6-11.8 l/100 km (20.3-20.6 US mpg) |
| CO2 Emissions | 277-282 g/km |
| Acceleration 0-100 km/h | 5.9 sec |
| Acceleration 0-60 mph | 5.6 sec |
| Maximum Speed | 250 km/h (155.34 mph) |
| Engine Layout | Front, Longitudinal |
| Engine Model/Code | M 273.924 |
| Engine Displacement | 4663 cm3 (284.55 cu. in.) |
| Number of Cylinders | 8 |
| Engine Configuration | V-engine |
| Cylinder Bore | 92.9 mm (3.66 in.) |
| Piston Stroke | 86 mm (3.39 in.) |
| Compression Ratio | 10.5:1 |
| Fuel Injection System | Multi-port manifold injection |
| Engine Oil Capacity | 8.5 l (8.98 US qt | 7.48 UK qt) |
| Coolant Capacity | 8.5 l (8.98 US qt | 7.48 UK qt) |
| Kerb Weight | 1935 kg (4265.94 lbs.) |
| Max. Weight | 2620 kg (5776.11 lbs.) |
| Trunk (Boot) Space (Maximum) | 560 l (19.78 cu. ft.) |
| Fuel Tank Capacity | 90 l (23.78 US gal | 19.8 UK gal) |
| Length | 5079 mm (199.96 in.) |
| Width | 1872 mm (73.7 in.) |
| Height | 1473 mm (57.99 in.) |
| Wheelbase | 3035 mm (119.49 in.) |
| Gearbox | 7 gears, automatic transmission G-TRONIC |
| Drive Wheel | All wheel drive (4×4) |
Legacy
The M273 engine, found in the S 450 4MATIC, has proven to be a relatively reliable powertrain when properly maintained. While the air suspension system can be prone to issues, regular servicing and preventative maintenance can mitigate these risks. On the used car market, the W221 S 450 4MATIC represents a compelling value proposition, offering a luxurious and well-equipped vehicle at a significantly lower price point than newer S-Class models. Its combination of performance, comfort, and all-wheel-drive capability continues to appeal to buyers seeking a refined and capable luxury sedan. The 7G-TRONIC transmission is also known for its durability, contributing to the long-term reliability of the vehicle. However, potential buyers should be aware of the potential for costly repairs related to the air suspension and electronic systems.
