2017-2020 BMW 5 Series Sedan (G30) M550d (400 Hp) xDrive Steptronic

Technical Specifications

The G30 generation BMW 5 Series, launched in 2017, represented a significant evolution of BMW’s executive sedan. The M550d xDrive Steptronic, introduced within this generation, was designed to bridge the gap between the more conventional 5 Series models and the high-performance M5. Utilizing a potent diesel engine and BMW’s xDrive all-wheel-drive system, it offered a unique combination of performance, efficiency, and luxury. The G30 platform incorporated advancements in lightweight construction, chassis technology, and driver assistance systems, all contributing to a more refined and engaging driving experience.

Powertrain & Engine Architecture

At the heart of the M550d lies the B57D30C, a 3.0-liter inline-six diesel engine. This engine is a masterpiece of modern diesel technology, featuring a sophisticated common-rail direct injection system and a twin-turbocharger setup. The two turbochargers are sequentially staged, with a smaller turbo providing boost at low engine speeds for improved responsiveness, and a larger turbo taking over at higher speeds for maximum power. The engine also incorporates an intercooler to further enhance performance by cooling the intake air. The B57 engine family is known for its robustness and ability to handle significant power output. The M550d’s version produces 400 horsepower at 4,400 rpm and a substantial 760 Nm (560 lb-ft) of torque between 2,000 and 3,000 rpm. This torque output is a key characteristic of the engine, providing effortless acceleration in virtually any gear.

The engine is paired with BMW’s 8-speed Steptronic automatic transmission. This transmission is renowned for its smooth and quick shifts, and it is specifically tuned to complement the characteristics of the diesel engine. The Steptronic transmission offers both automatic and manual shift modes, allowing the driver to take control when desired. The xDrive all-wheel-drive system distributes power between the front and rear axles as needed, providing optimal traction and stability in all weather conditions.

Driving Characteristics

The M550d delivers a remarkably refined and powerful driving experience. The abundant torque from the diesel engine provides effortless acceleration, making overtaking and merging onto highways a breeze. The 0-60 mph sprint is dispatched in around 4.2 seconds, a figure that rivals many sports cars. Despite its size and weight, the M550d feels surprisingly agile and composed, thanks to its well-tuned chassis and xDrive all-wheel-drive system. The steering is precise and well-weighted, providing good feedback to the driver. The 8-speed automatic transmission shifts smoothly and efficiently, contributing to a relaxed and comfortable driving experience. Compared to the gasoline-powered 540i, the M550d offers superior fuel economy and a broader torque curve, making it a more practical choice for long-distance driving. However, it lacks the high-revving excitement and sound of the gasoline engine.

Equipment & Trim Levels

The M550d xDrive Steptronic came generously equipped as standard. Typical features included leather upholstery, power-adjustable front seats with memory function, a premium sound system, a large infotainment screen with navigation, and a comprehensive suite of driver assistance systems, such as adaptive cruise control, lane departure warning, and automatic emergency braking. Optional extras included features like massaging seats, a head-up display, and a panoramic sunroof. The interior design was typically BMW, with a focus on quality materials and a driver-centric layout. The M550d also featured unique exterior styling cues, such as M Sport aerodynamic enhancements and distinctive wheels, to differentiate it from other 5 Series models.

Chassis & Braking

The M550d’s chassis was specifically tuned to handle the increased power and torque of the diesel engine. It featured a robust suspension system with adaptive dampers, allowing the driver to adjust the ride comfort and handling characteristics. The suspension geometry was optimized to minimize body roll and maximize grip. The braking system consisted of ventilated discs on all four wheels, providing ample stopping power. The ABS (Anti-lock Braking System) and stability control systems worked in conjunction to ensure safe and controlled braking in all conditions.

Market Reception & Comparison

The M550d was generally well-received by automotive critics. It was praised for its impressive performance, fuel efficiency, and luxurious interior. However, some critics noted that the diesel engine lacked the emotional appeal of a gasoline engine. Compared to the 540i, the M550d offered superior fuel economy and torque, but it was slightly slower in acceleration. Compared to the M5, the M550d was less focused on outright performance but offered a more comfortable and refined driving experience. The M550d’s fuel economy figures of around 39.9-38.6 US mpg combined were a significant advantage over its gasoline-powered counterparts.

Legacy

The B57 engine family, including the B57D30C used in the M550d, has proven to be remarkably reliable. With proper maintenance, these engines can easily exceed 200,000 miles. The M550d has become a popular choice in the used car market, offering a compelling combination of performance, luxury, and value. However, potential buyers should be aware of the potential maintenance costs associated with a diesel engine, such as diesel particulate filter (DPF) maintenance and potential issues with the fuel injection system. Overall, the M550d xDrive Steptronic remains a highly desirable and capable executive sedan.