The BMW 3 Series Touring (G21) M340d xDrive Steptronic, produced from February 2020 to 2022, represents a high-performance variant within the sixth generation of the 3 Series Touring (estate) model line. Positioned as a premium offering, it combines a potent diesel engine with mild-hybrid technology and BMW’s xDrive all-wheel-drive system. This model aimed to deliver both exhilarating performance and improved fuel efficiency within the practical framework of a five-door station wagon. It sits at the top of the non-M performance trims, offering a significant step up in power and refinement compared to lower-spec 3 Series Touring models like the 320d or 330i.
Technical Specifications
| Brand | BMW |
| Model | 3 Series |
| Generation | 3 Series Touring (G21) |
| Type (Engine) | M340d (340 Hp) Mild Hybrid xDrive Steptronic |
| Start of production | February, 2020 |
| End of production | 2022 |
| Powertrain Architecture | MHEV (Mild Hybrid Electric Vehicle) |
| Body type | Station wagon (estate) |
| Seats | 5 |
| Doors | 5 |
| Fuel consumption (urban) | 7.3-7.8 l/100 km (32.2 – 30.2 US mpg) |
| Fuel consumption (extra urban) | 4.3-4.7 l/100 km (54.7 – 50 US mpg) |
| Fuel consumption (combined) | 5.4-5.8 l/100 km (43.6 – 40.6 US mpg) |
| CO2 emissions | 143-153 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 4.8 sec |
| Acceleration 0 – 62 mph | 4.8 sec |
| Acceleration 0 – 60 mph | 4.6 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Emission standard | Euro 6d |
| Weight-to-power ratio | 5.5 kg/Hp |
| Weight-to-torque ratio | 2.7 kg/Nm |
| Battery voltage | 48 V |
| Battery technology | Lithium-ion (Li-Ion) |
| Electric motor power | 11 Hp |
| Power | 340 Hp @ 4400 rpm |
| Torque | 700 Nm @ 1750-2250 rpm (516.29 lb.-ft. @ 1750-2250 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B57D30A |
| Engine displacement | 2993 cm3 (182.64 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 84 mm (3.31 in.) |
| Piston Stroke | 90 mm (3.54 in.) |
| Compression ratio | 16.5:1 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Twin-power turbo, Intercooler |
| Valvetrain | DOHC |
| Engine oil capacity | 7 l (7.4 US qt | 6.16 UK qt) |
| Coolant capacity | 7.7 l (8.14 US qt | 6.78 UK qt) |
| Kerb Weight | 1880 kg (4144.69 lbs.) |
| Max. weight | 2415 kg (5324.16 lbs.) |
| Max load | 535 kg (1179.47 lbs.) |
| Trunk (boot) space – minimum | 500 l (17.66 cu. ft.) |
| Trunk (boot) space – maximum | 1510 l (53.33 cu. ft.) |
| Fuel tank capacity | 59 l (15.59 US gal | 12.98 UK gal) |
| Length | 4713 mm (185.55 in.) |
| Width | 1827 mm (71.93 in.) |
| Height | 1440 mm (56.69 in.) |
| Wheelbase | 2851 mm (112.24 in.) |
| Front track | 1583 mm (62.32 in.) |
| Rear track | 1567 mm (61.69 in.) |
| Ride height (ground clearance) | 130 mm (5.12 in.) |
| Drag coefficient (Cd) | 0.28 |
| Minimum turning circle | 12 m (39.37 ft.) |
| Drive wheel | All wheel drive (4×4) |
| Number of gears | 8 |
| Gearbox type | automatic transmission Steptronic |
INTRODUCTION
The G21 3 Series Touring, launched in 2019, marked the return of the 3 Series wagon to the North American market after a lengthy absence. The M340d xDrive Steptronic, introduced in 2020, was a key variant, particularly in Europe and other markets where diesel engines remain popular. It combined the practicality of the Touring body style with the performance credentials of BMW’s M Performance Automobiles line. The mild-hybrid system, a 48V setup, provided a small power boost and enabled smoother start-stop operation, contributing to improved fuel economy and reduced emissions. This model was designed to appeal to buyers seeking a versatile, efficient, and dynamically engaging vehicle.
Powertrain & Engine Architecture
At the heart of the M340d lies the B57D30A, a 3.0-liter inline-six diesel engine. This engine utilizes a sophisticated diesel commonrail fuel injection system, delivering precise fuel metering for optimal combustion. The B57 features a twin-scroll turbocharger with variable geometry turbine (VGT) technology, enhancing both low-end torque and high-end power. The engine also incorporates an intercooler to cool the intake air, further improving performance. The 48V mild-hybrid system adds a small electric motor integrated into the drivetrain, providing up to 11 horsepower of assistance during acceleration and enabling coasting with the engine shut off. The engine’s DOHC valvetrain, with four valves per cylinder, optimizes gas flow for increased efficiency and power. The Steptronic 8-speed automatic transmission is specifically tuned for the M340d, offering smooth and responsive gear changes. It features optimized shift points for performance and efficiency, and includes paddle shifters for manual control.
Driving Characteristics
The M340d xDrive Steptronic delivers a compelling driving experience. The 700 Nm (516 lb-ft) of torque, available from 1750-2250 rpm, provides effortless acceleration in everyday driving situations. The xDrive all-wheel-drive system ensures excellent traction in all weather conditions, while the M Sport suspension (often equipped as standard or optional) provides a firm yet controlled ride. Compared to the 320d or 330i Touring models, the M340d offers significantly more power and a more responsive feel. While not as overtly sporty as the M3, the M340d provides a satisfying balance of performance and comfort. The 8-speed automatic transmission is well-matched to the engine, providing quick and seamless gear changes. The mild-hybrid system contributes to a smoother driving experience, particularly during start-stop transitions.
Equipment & Trim Levels
The M340d xDrive Steptronic typically came well-equipped as standard. Common features included BMW’s Live Cockpit Professional (digital instrument cluster and infotainment system), leather upholstery, M Sport seats, automatic climate control, and a comprehensive suite of driver-assistance systems such as lane departure warning, forward collision warning, and automatic emergency braking. Optional extras included a head-up display, Harman Kardon premium sound system, panoramic sunroof, and adaptive cruise control. Interior trim options varied, with choices ranging from aluminum to wood accents. The exterior styling was enhanced with M Sport aerodynamic elements, including a unique front bumper, side skirts, and rear diffuser.
Chassis & Braking
The G21 3 Series Touring features a sophisticated chassis design. The front suspension utilizes a MacPherson strut setup with a transverse stabilizer bar, while the rear suspension employs a multi-link independent suspension, also with a stabilizer bar. The M340d typically featured stiffer springs and dampers compared to lower-spec models, enhancing handling and stability. The braking system consisted of ventilated discs on all four wheels, providing ample stopping power. The xDrive all-wheel-drive system utilizes a multi-plate clutch to distribute torque between the front and rear axles, optimizing traction and stability. The steering system is an electric power-assisted rack-and-pinion setup, offering precise and responsive steering feel.
Market Reception & Comparison
The M340d xDrive Steptronic was generally well-received by automotive critics. It was praised for its powerful engine, refined ride, and practical versatility. Compared to the gasoline-powered M340i, the M340d offered superior fuel economy and a broader torque curve, making it a more relaxed and efficient cruiser. However, some critics noted that the diesel engine lacked the aural excitement of the gasoline counterpart. Against competitors like the Audi A6 Avant and Mercedes-Benz E-Class Estate, the M340d was considered a strong contender, offering a compelling blend of performance, luxury, and practicality.
Legacy
The B57 engine family, including the B57D30A used in the M340d, has proven to be remarkably reliable. While diesel engines generally require diligent maintenance, these engines are known for their durability and longevity. On the used car market, the G21 3 Series Touring M340d holds its value well, reflecting its desirable combination of performance, practicality, and refinement. The mild-hybrid technology, while relatively early in its development, has contributed to improved fuel efficiency and reduced emissions, making this model a more environmentally conscious choice. The M340d represents a significant step forward in the evolution of the 3 Series Touring, offering a compelling alternative to traditional gasoline-powered performance wagons.
