The BMW 4 Series Convertible (G23) M440i, produced from 2020 through January 2024, represents a compelling blend of performance, luxury, and open-air driving enjoyment. Positioned as a mid-to-high range trim within the G23 generation, it serves as a step up from the 430i models, offering significantly more power and a more sophisticated driving experience. This variant is characterized by its 3.0-liter inline-six engine, mild hybrid technology, and xDrive all-wheel-drive system, paired with an 8-speed Steptronic automatic transmission. The G23 generation itself is based on the BMW Cluster Architecture (CLAR) platform, emphasizing lightweight construction and optimized packaging.
Technical Specifications
| Brand | BMW |
| Model | 4 Series |
| Generation | 4 Series Convertible (G23) |
| Type | M440i (382 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 |
| Fuel consumption (urban) | 10.7 l/100 km (22 US mpg) |
| Fuel consumption (extra urban) | 7.8 l/100 km (30.2 US mpg) |
| Fuel consumption (combined) | 9.4 l/100 km (25 US mpg) |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 60 mph | 4.7 sec |
| Maximum speed | 210 km/h (130.49 mph) |
| Weight-to-power ratio | 5.1 kg/Hp |
| Weight-to-torque ratio | 3.9 kg/Nm |
| Gross battery capacity | 0.4 kWh |
| Battery voltage | 48 V |
| Battery technology | Lithium-ion (Li-Ion) |
| Electric motor power | 11 Hp |
| Electric motor Torque | 25 Nm (18.44 lb.-ft.) |
| Power | 382 Hp @ 5800-6500 rpm |
| Torque | 500 Nm @ 1800-5000 rpm (368.78 lb.-ft. @ 1800-5000 rpm) |
| Engine displacement | 2998 cm3 (182.95 cu. in.) |
| Number of cylinders | 6 |
| Engine Code | B58B30O1 |
| Kerb Weight | 1947 kg (4292.4 lbs.) |
| Max. weight | 2355 kg (5191.89 lbs.) |
| Trunk space (min) | 300 l (10.59 cu. ft.) |
| Trunk space (max) | 385 l (13.6 cu. ft.) |
| Fuel tank capacity | 59 l (15.59 US gal) |
| Length | 4775 mm (187.99 in.) |
| Width | 1852 mm (72.91 in.) |
| Height | 1394 mm (54.88 in.) |
| Wheelbase | 2851 mm (112.24 in.) |
| Gearbox | 8-speed automatic (Steptronic) |
Powertrain & Engine Architecture
At the heart of the M440i Convertible lies the BMW B58B30O1 3.0-liter inline-six engine. This engine is a member of the B58 family, known for its smooth power delivery and robust construction. It utilizes direct fuel injection, a twin-scroll turbocharger, and BMW’s VALVETRONIC fully variable valve timing and Double-VANOS variable camshaft timing systems. These technologies work in concert to optimize efficiency and performance across the engine’s operating range. The addition of a 48V mild hybrid system provides an extra 11 horsepower and 25 Nm of torque, assisting the engine during acceleration and enabling smoother start-stop operation. The 8-speed Steptronic automatic transmission is a cornerstone of the driving experience, offering quick and precise shifts. It features a torque converter and allows for both automatic and manual gear selection via steering wheel-mounted paddles.
Driving Characteristics
The M440i Convertible delivers a refined yet engaging driving experience. The 382 horsepower and 500 Nm (368 lb-ft) of torque provide brisk acceleration, with a 0-60 mph time of just 4.7 seconds. The xDrive all-wheel-drive system ensures excellent traction in various conditions, distributing power between the front and rear axles as needed. Compared to the 430i Convertible, the M440i offers a noticeable increase in performance, particularly in mid-range acceleration. While the 430i prioritizes fuel efficiency, the M440i leans towards a more sporty character. The Steptronic transmission is well-tuned, providing seamless gear changes in automatic mode and responsive control when shifting manually. The suspension strikes a good balance between comfort and handling, making it suitable for both daily driving and spirited weekend excursions.
Equipment & Trim Levels
The M440i Convertible came standard with a comprehensive list of features, including leather upholstery, power-adjustable seats with memory function, a premium sound system, and a large infotainment display with iDrive controller. Standard safety features included automatic emergency braking, lane departure warning, and adaptive cruise control. Optional extras included upgraded leather options, a head-up display, parking assist, and a wind deflector to reduce turbulence in the cabin when the top is down. The interior design is typically BMW, with a focus on quality materials and a driver-centric layout. The dashboard features a sleek design with integrated controls and a digital instrument cluster.
Chassis & Braking
The G23 M440i Convertible utilizes a sophisticated chassis design to deliver a comfortable and controlled ride. The front suspension features spring struts with a transverse stabilizer, while the rear suspension employs an independent multi-link setup, also with a stabilizer bar. This configuration helps to minimize body roll and maximize grip. The braking system consists of ventilated discs on all four wheels, providing ample stopping power. Anti-lock braking system (ABS) and electronic stability control (ESC) are standard features, enhancing safety and stability. The steering system is an electric power-assisted rack-and-pinion setup, offering precise and responsive steering feel.
Market Reception & Comparison
The M440i Convertible was generally well-received by automotive critics, who praised its powerful engine, refined handling, and luxurious interior. It was often compared to rivals such as the Audi A5 Cabriolet and Mercedes-Benz C-Class Cabriolet. While the M440i offered a compelling combination of performance and comfort, some reviewers noted that its fuel economy was not as competitive as some of its rivals. However, the M440i’s overall driving experience and build quality were consistently praised. Compared to the 430i Convertible, the M440i represented a significant upgrade in terms of performance and features, justifying its higher price tag for buyers seeking a more engaging driving experience.
Legacy
The B58 engine family, including the B58B30O1 found in the M440i, has proven to be remarkably reliable. While some early examples experienced minor issues with the cooling system, these were largely addressed through software updates and revised components. The 8-speed Steptronic transmission is also known for its durability. As a result, well-maintained M440i Convertibles are expected to provide years of reliable service. On the used car market, the G23 M440i Convertible holds its value relatively well, reflecting its desirable combination of performance, luxury, and open-air driving enjoyment. It remains a popular choice for buyers seeking a premium convertible experience.
