The BMW 4 Series Convertible (G23 LCI), specifically the M440i xDrive Steptronic model, represents the facelifted iteration of the G23 generation, introduced for the 2025 model year. This variant occupies the performance-oriented, near-top position within the 4 Series Convertible lineup, slotting below any potential future high-performance ‘M’ variants. The LCI (Life Cycle Impulse) updates brought revised styling, enhanced technology, and refinements to the powertrain. It builds upon the foundation of the G23 platform, which debuted in 2020, offering a blend of open-air driving enjoyment and modern BMW performance. The M440i xDrive is targeted towards buyers seeking a luxurious and capable convertible with strong acceleration and all-weather capability.
Technical Specifications
| Brand | BMW |
| Model | 4 Series |
| Generation | 4 Series Convertible (G23 LCI, facelift 2024) |
| Type (Engine) | M440i (392 Hp) Mild Hybrid xDrive Steptronic |
| Start of production | September, 2025 |
| Powertrain Architecture | MHEV (Mild Hybrid Electric Vehicle) |
| Body type | Cabriolet |
| Seats | 4 |
| Doors | 2 |
| Combined fuel consumption (WLTP) | 7.7 l/100 km (30.5 US mpg, 36.7 UK mpg, 13 km/l) |
| CO2 emissions (WLTP) | 176 g/km |
| Fuel Type | Petrol (Gasoline) |
| 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), Electronically limited |
| Emission standard | Euro 6e |
| Weight-to-power ratio | 4.9 kg/Hp, 203.6 Hp/tonne |
| Weight-to-torque ratio | 3.6 kg/Nm, 280.5 Nm/tonne |
| Gross battery capacity | 0.4 kWh |
| Battery voltage | 48 V |
| Battery technology | Lithium-ion (Li-Ion) |
| Battery location | Under the front hood |
| Electric motor power | 12 Hp |
| Electric motor Torque | 200 Nm (147.51 lb.-ft.) |
| Electric motor location | Front, Longitudinal |
| System power | 392 Hp |
| Power | 381 Hp @ 5200-6250 rpm |
| Power per litre | 127.1 Hp/l |
| Torque | 540 Nm @ 1900-4800 rpm (398.28 lb.-ft. @ 1900-4800 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B58 |
| Engine displacement | 2998 cm3 (182.95 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 82 mm (3.23 in.) |
| Piston Stroke | 94.6 mm (3.72 in.) |
| Number of valves per cylinder | 4 |
| Fuel injection system | Direct injection |
| Engine aspiration | Twin-scroll turbo, Intercooler |
| Valvetrain | Double-VANOS, VALVETRONIC |
| Engine systems | Start & Stop System, Particulate filter |
| Kerb Weight | 1925 kg (4243.9 lbs.) |
| Max. weight | 2410 kg (5313.14 lbs.) |
| Max load | 485 kg (1069.24 lbs.) |
| Trunk (boot) space – minimum | 385 l (13.6 cu. ft.) |
| Fuel tank capacity | 59 l (15.59 US gal | 12.98 UK gal) |
| Permitted trailer load with brakes (12%) | 1800 kg (3968.32 lbs.) |
| Permitted trailer load without brakes | 750 kg (1653.47 lbs.) |
| Permitted towbar download | 75 kg (165.35 lbs.) |
| Length | 4770 mm (187.8 in.) |
| Width | 1852 mm (72.91 in.) |
| Width including mirrors | 2081 mm (81.93 in.) |
| Height | 1394 mm (54.88 in.) |
| Wheelbase | 2851 mm (112.24 in.) |
| Front track | 1583 mm (62.32 in.) |
| Rear (Back) track | 1592 mm (62.68 in.) |
| Front overhang | 858 mm (33.78 in.) |
| Rear overhang | 1061 mm (41.77 in.) |
| Ride height (ground clearance) | 126 mm (4.96 in.) |
| Minimum turning circle (turning diameter) | 12 m (39.37 ft.) |
| Drivetrain Architecture | ICE and electric motor drive all four wheels, mixed mode operation |
| Drive wheel | All wheel drive (4×4) |
| Number of gears and type of gearbox | 8 gears, automatic transmission Steptronic |
| Front suspension | Spring Strut, Transverse stabilizer |
| Rear suspension | Independent multi-link spring suspension with stabilizer |
| 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 | Front: 225/45 R18 or 225/40 R19; Rear: 255/40 R18 or 255/35 R19 |
| Wheel rims size | Front: 7.5J x 18 or 8J x 19; Rear: 8.5J x 18 or 8.5J x 19 |
Powertrain & Engine Architecture
At the heart of the M440i xDrive lies the BMW B58 3.0-liter inline-six engine. This engine is a cornerstone of modern BMW performance, known for its smooth power delivery and responsiveness. The B58 utilizes direct fuel injection, a twin-scroll turbocharger, and an intercooler to produce 381 horsepower at 5200-6250 rpm and 540 Nm (398.28 lb.-ft.) of torque between 1900-4800 rpm. The ‘M40i’ designation signifies a higher state of tune compared to the standard 30i variants. Crucially, this engine incorporates 48V mild-hybrid technology. A 12 hp electric motor integrated into the drivetrain provides a power boost during acceleration and enables a smoother start-stop function. The 8-speed Steptronic automatic transmission is standard, optimized for both performance and efficiency. The transmission features a wide gear ratio spread and quick, precise shifts. The xDrive all-wheel-drive system intelligently distributes torque between the front and rear axles for optimal traction in all conditions.
Driving Characteristics
The M440i xDrive Convertible delivers a compelling driving experience. The combination of the potent B58 engine, the 8-speed automatic, and the xDrive system results in a 0-60 mph time of approximately 4.6 seconds. The mild-hybrid system provides an immediate torque fill, enhancing responsiveness from a standstill. While not as overtly sporty as a dedicated ‘M’ car, the M440i offers ample power for spirited driving. The automatic transmission is well-programmed, providing smooth upshifts and downshifts. Compared to the 430i Convertible, the M440i offers a significant performance advantage. The 430i’s 2.0-liter four-cylinder engine, while efficient, lacks the low-end torque and overall power of the inline-six. The xDrive system provides confident handling and stability, particularly on wet or slippery surfaces.
Equipment & Trim Levels
The M440i xDrive Convertible comes generously equipped as standard. Key features include leather upholstery, power-adjustable seats with memory function, a premium sound system, and a comprehensive suite of driver-assistance systems (including lane departure warning, forward collision warning, and automatic emergency braking). The infotainment system features a large touchscreen display with iDrive controller. Optional extras include upgraded leather trim, a head-up display, adaptive cruise control, and a parking assistant package. Exterior styling cues differentiate the M440i from lower trims, including unique alloy wheel designs, M Sport brakes, and subtle aerodynamic enhancements.
Chassis & Braking
The G23 Convertible utilizes a sophisticated chassis design. The front suspension employs spring struts with a transverse stabilizer, while the rear features an independent multi-link setup, also with a stabilizer bar. This configuration provides a good balance between ride comfort and handling precision. The M440i is equipped with ventilated disc brakes on all four wheels, providing ample stopping power. The braking system is further enhanced by ABS, electronic brake-force distribution, and brake assist. The steering is electrically assisted, offering precise and responsive control.
Market Reception & Comparison
The BMW 4 Series Convertible (G23 LCI) M440i xDrive has been generally well-received by automotive critics. Reviewers praise its powerful engine, refined ride quality, and luxurious interior. The mild-hybrid system is noted for its contribution to improved fuel economy and smoother operation. Compared to competitors such as the Audi A5 Cabriolet and Mercedes-Benz C-Class Cabriolet, the M440i is often cited as offering a more engaging driving experience. Fuel economy is rated at 7.7 l/100 km (30.5 US mpg), which is competitive for a performance convertible. Reliability appears to be generally good, although long-term data is still emerging.
Legacy
The B58 engine has proven to be a robust and reliable powerplant, and is expected to provide years of dependable service. The 48V mild-hybrid system, while relatively new, is also showing promise in terms of durability. The G23 generation 4 Series Convertible, and particularly the M440i variant, is likely to hold its value well in the used car market due to its combination of performance, luxury, and open-air driving appeal. As technology continues to evolve, the M440i xDrive represents a transitional model, bridging the gap between traditional internal combustion engines and the future of electrified performance.
