The BMW 4 Series Convertible (G23) M440i, produced from 2020 through January 2024, represents a compelling blend of performance and open-air driving enjoyment within the broader G23 generation. Positioned as a mid-to-high range trim, the M440i distinguishes itself with a potent mild-hybrid powertrain and standard xDrive all-wheel drive. It caters to drivers seeking a more engaging experience than the base 430i models, while offering a slightly more accessible entry point into the performance-oriented M variants. This model occupies a key space in BMW’s lineup, bridging the gap between luxury and sporty driving dynamics in a convertible format.
Technical Specifications
| Brand | BMW |
| Model | 4 Series |
| Generation | 4 Series Convertible (G23) |
| Type | M440i (374 Hp) Mild Hybrid xDrive Steptronic |
| Start of production | 2020 |
| End of production | January, 2024 |
| Powertrain Architecture | MHEV (Mild Hybrid Electric Vehicle) |
| Body type | Cabriolet |
| Seats | 4 |
| Doors | 2 |
| Combined fuel consumption (WLTP) | 7.8-8.4 l/100 km (30.2 – 28 US mpg, 36.2 – 33.6 UK mpg, 12.8 – 11.9 km/l) |
| CO2 emissions (WLTP) | 177-192 g/km |
| Fuel consumption (urban – NEDC) | 8.9-9.3 l/100 km (26.4 – 25.3 US mpg, 31.7 – 30.4 UK mpg, 11.2 – 10.8 km/l) |
| Fuel consumption (extra urban – NEDC) | 5.8-6.2 l/100 km (40.6 – 37.9 US mpg, 48.7 – 45.6 UK mpg, 17.2 – 16.1 km/l) |
| Fuel consumption (combined – NEDC) | 6.9-7.4 l/100 km (34.1 – 31.8 US mpg, 40.9 – 38.2 UK mpg, 14.5 – 13.5 km/l) |
| CO2 emissions (NEDC) | 159-169 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 4.9 sec |
| Acceleration 0 – 62 mph | 4.9 sec |
| Acceleration 0 – 60 mph | 4.7 sec |
| Maximum speed | 250 km/h (155.34 mph), Electronically limited |
| Emission standard | Euro 6d |
| Weight-to-power ratio | 5.1 kg/Hp, 197.9 Hp/tonne |
| Weight-to-torque ratio | 3.8 kg/Nm, 264.6 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 | 11 Hp |
| Electric motor Torque | 25 Nm (18.44 lb.-ft.) |
| Electric motor location | Front, Longitudinal |
| Power | 374 Hp @ 5500-6500 rpm |
| Torque | 500 Nm @ 1900-5000 rpm (368.78 lb.-ft. @ 1900-5000 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B58B30B |
| 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.) |
| Compression ratio | 10.2:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Direct injection |
| Engine aspiration | Twin-power turbo, Intercooler |
| Valvetrain | Double-VANOS, VALVETRONIC |
| Engine oil capacity | 7.2 l (7.61 US qt | 6.34 UK qt) |
| Coolant capacity | 10.5 l (11.1 US qt | 9.24 UK qt) |
| Kerb Weight | 1890 kg (4166.74 lbs.) |
| Max. weight | 2390 kg (5269.05 lbs.) |
| Max load | 500 kg (1102.31 lbs.) |
| Trunk (boot) space – minimum | 300 l (10.59 cu. ft.) |
| Trunk (boot) space – maximum | 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.) |
| Height | 1394 mm (54.88 in.) |
| Wheelbase | 2851 mm (112.24 in.) |
| Front track | 1575 mm (62.01 in.) |
| Rear track | 1611 mm (63.43 in.) |
| Ride height (ground clearance) | 126 mm (4.96 in.) |
| Drag coefficient (Cd) | 0.28 |
| Minimum turning circle | 12.0 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 | 8 |
| Gearbox type | 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 |
| Front tires | 225/45 R18 |
| Rear tires | 255/40 R18 99 |
| Front wheel rims | 7.5J x 18 |
| Rear wheel rims | 8.5J x 18 |
Powertrain & Engine Architecture
At the heart of the M440i lies BMW’s B58B30B 3.0-liter inline-six engine. This engine benefits from a single twin-scroll turbocharger, direct fuel injection, and BMW’s VALVETRONIC and Double-VANOS technologies for optimized efficiency and responsiveness. The addition of a 48V mild-hybrid system provides an electric boost of 11 horsepower and 25 Nm (18.44 lb-ft) of torque, aiding in smoother starts and improved fuel economy. The engine produces 374 horsepower at 5500-6500 rpm and 500 Nm (368.78 lb-ft) of torque between 1900-5000 rpm. This power is channeled through an eight-speed Steptronic automatic transmission, which is known for its quick and smooth shifts. The xDrive all-wheel-drive system intelligently distributes power between the front and rear axles for optimal traction in various conditions.
Driving Characteristics
The M440i Convertible delivers a refined yet engaging driving experience. The mild-hybrid system provides immediate torque fill, minimizing turbo lag and enhancing responsiveness. The eight-speed automatic transmission is well-tuned, offering both seamless automatic shifts and responsive manual control. While not as overtly sporty as a full-fledged M car, the M440i offers ample power for spirited driving, achieving 0-60 mph in approximately 4.7 seconds. The xDrive system provides confident handling and stability, particularly in inclement weather. The convertible top operation doesn’t significantly impact the chassis rigidity, maintaining a composed ride even with the top down.
Equipment & Trim Levels
The M440i Convertible came standard with a comprehensive suite of features, including BMW’s iDrive infotainment system with a 12.3-inch touchscreen, navigation, Apple CarPlay and Android Auto compatibility, and a premium sound system. Standard interior appointments included leather upholstery, power-adjustable sport seats, and ambient lighting. Optional extras included upgraded leather options, a head-up display, parking assistance systems, and advanced driver-assistance features like adaptive cruise control and lane-keeping assist. The M Sport package added unique exterior styling elements, sport suspension, and M Sport brakes.
Chassis & Braking
The G23 M440i utilizes a sophisticated chassis design featuring a spring strut front suspension and an independent multi-link rear suspension, both incorporating a transverse stabilizer bar. This setup provides a balance between comfort and handling. The braking system consists of ventilated discs at all four corners, providing ample stopping power. The standard ABS (Anti-lock braking system) and electronic stability control further enhance safety. The vehicle’s weight distribution is carefully optimized to contribute to its balanced handling characteristics.
Market Reception & Comparison
The M440i Convertible was generally well-received by automotive critics, praised for its potent powertrain, refined driving dynamics, and luxurious interior. Compared to the base 430i models, the M440i offered a significant performance upgrade. While the M4 Convertible provided even more extreme performance, the M440i struck a balance between sportiness and everyday usability. Fuel economy was respectable for a performance convertible, with combined figures ranging from 7.8-8.4 l/100 km. Reliability reports have been generally positive, with the B58 engine proving to be a robust and dependable unit.
Legacy
The BMW 4 Series Convertible (G23) M440i represents a modern interpretation of the classic BMW convertible experience. The B58 engine, coupled with the mild-hybrid technology and xDrive all-wheel drive, provides a compelling combination of performance, efficiency, and all-weather capability. On the used car market, these models hold their value well, appealing to buyers seeking a premium convertible with a sporty character. The robust powertrain and well-engineered chassis suggest long-term reliability, making the M440i a desirable option for enthusiasts and discerning drivers alike.
