The BMW 4 Series Convertible (G23 LCI), specifically the 430d variant with 286 horsepower and a mild-hybrid Steptronic automatic transmission, represents a mid-cycle refresh of the G23 generation launched in March 2024. This model sits within the broader 4 Series lineup, offering a blend of performance, luxury, and open-air driving experience. The “LCI” (Life Cycle Impulse) designation signifies a significant facelift, incorporating updated styling, technology, and powertrain refinements. The 430d is positioned as a premium offering within the 4 Series Convertible range, appealing to buyers seeking a balance between spirited driving and fuel efficiency, particularly in European markets where diesel engines remain popular.
Technical Specifications
| Brand | BMW |
| Model | 4 Series |
| Generation | 4 Series Convertible (G23 LCI, facelift 2024) |
| Type (Engine) | 430d (286 Hp) Mild Hybrid Steptronic |
| Start of production | March, 2024 |
| Powertrain Architecture | MHEV (Mild Hybrid Electric Vehicle) |
| Body type | Cabriolet |
| Seats | 4 |
| Doors | 2 |
| Combined fuel consumption (WLTP) | 5.2-5.8 l/100 km (45.2 – 40.6 US mpg) |
| CO2 emissions (WLTP) | 146-164 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 5.8 sec |
| Acceleration 0 – 62 mph | 5.8 sec |
| Acceleration 0 – 60 mph | 5.5 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Emission standard | Euro 6e |
| Weight-to-power ratio | 6.6 kg/Hp |
| Weight-to-torque ratio | 2.9 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 | 286 Hp @ 4000 rpm |
| Torque | 650 Nm @ 1500-2500 rpm (479.42 lb.-ft. @ 1500-2500 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B57 |
| 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) |
| Kerb Weight | 1885 kg (4155.71 lbs.) |
| Max. weight | 2370 kg (5224.96 lbs.) |
| Max load | 485 kg (1069.24 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.) |
| Length | 4768 mm (187.72 in.) |
| Width | 1852 mm (72.91 in.) |
| Width including mirrors | 2081 mm (81.93 in.) |
| Height | 1384 mm (54.49 in.) |
| Wheelbase | 2851 mm (112.24 in.) |
| Front track | 1573 mm (61.93 in.) |
| Rear track | 1612 mm (63.46 in.) |
| Front overhang | 858 mm (33.78 in.) |
| Rear overhang | 1059 mm (41.69 in.) |
| Ride height (ground clearance) | 124 mm (4.88 in.) |
| Drag coefficient (Cd) | 0.28 |
| Minimum turning circle | 11.4 m (37.4 ft.) |
| Drivetrain | Rear wheel drive. MHEV. |
| Number of gears | 8 |
| Gearbox type | Automatic transmission Steptronic |
Powertrain & Engine Architecture
At the heart of the 430d Convertible LCI lies the BMW B57 3.0-liter inline-six diesel engine. This engine is a cornerstone of BMW’s diesel offerings, known for its refinement and strong torque output. The B57 utilizes a sophisticated diesel commonrail fuel injection system, delivering precise fuel metering for optimal combustion. It’s equipped with a twin-turbocharger setup – a low-pressure turbo combined with a high-pressure turbo – to minimize turbo lag and provide a broad torque curve. The engine also features an intercooler to further enhance performance by cooling the intake air. The 2024 LCI incorporates a 48V mild-hybrid system, adding a small electric motor that provides a power boost during acceleration and enables smoother start-stop operation. This system contributes to improved fuel economy and reduced emissions. The engine produces 286 horsepower at 4000 rpm and a substantial 650 Nm (479.42 lb-ft) of torque between 1500 and 2500 rpm. This torque is delivered to the rear wheels via an eight-speed Steptronic automatic transmission, known for its quick and smooth shifts.
Driving Characteristics
The 430d Convertible with the Steptronic transmission offers a refined and comfortable driving experience. The abundance of low-end torque from the diesel engine makes for effortless cruising and strong acceleration in everyday driving situations. While not as overtly sporty as some of the gasoline-powered 4 Series variants, the 430d provides ample power for spirited driving, achieving 0-60 mph in approximately 5.5 seconds. The eight-speed automatic transmission is well-tuned, providing seamless gear changes and contributing to the car’s overall smoothness. The mild-hybrid system provides a subtle but noticeable boost during acceleration, enhancing responsiveness. Compared to a manual transmission version (if offered), the Steptronic prioritizes convenience and ease of use, making it ideal for daily commutes and long-distance journeys. Compared to higher-output 4 Series models like the M440i, the 430d offers a more relaxed and fuel-efficient driving experience, sacrificing some outright performance for improved economy.
Equipment & Trim Levels
The 430d Convertible LCI typically comes well-equipped as standard. Key features include BMW’s iDrive infotainment system with a touchscreen display, navigation, Apple CarPlay and Android Auto integration, and a premium sound system. Interior upholstery is typically leatherette or leather, with a choice of colors and trim options. Standard safety features include automatic emergency braking, lane departure warning, and parking sensors. Optional extras available for the 430d include upgraded leather upholstery, a head-up display, adaptive cruise control, a panoramic sunroof, and various driver-assistance systems. The LCI facelift brought updated interior trim options and enhanced connectivity features.
Chassis & Braking
The 4 Series Convertible utilizes a sophisticated chassis design. The front suspension employs spring struts with a transverse stabilizer, while the rear features an independent multi-link spring suspension, also with a stabilizer bar. This setup provides a good balance between ride comfort and handling precision. The 430d Convertible is equipped with ventilated disc brakes on all four wheels, providing ample stopping power. Anti-lock braking system (ABS) and electronic stability control (ESC) are standard features. The suspension tuning is geared towards providing a comfortable ride, but the car still offers a reasonably engaging driving experience, particularly in Sport mode.
Market Reception & Comparison
The 430d Convertible LCI has been generally well-received by automotive critics. Reviewers praise its refined engine, comfortable ride, and well-appointed interior. The fuel economy of the diesel engine is a significant selling point, particularly in Europe. Compared to the gasoline-powered 4 Series variants, the 430d offers a more economical option without sacrificing too much performance. However, some critics note that the diesel engine lacks the aural excitement of the gasoline engines. Reliability reports suggest that the B57 engine is generally robust, but regular maintenance is crucial for long-term durability.
Legacy
The B57 engine has proven to be a reliable and durable powerplant in BMW’s lineup. The mild-hybrid integration in the LCI model further enhances its efficiency and reduces emissions. On the used car market, well-maintained 430d Convertibles are likely to hold their value due to their combination of performance, luxury, and fuel economy. The 430d represents a compelling option for buyers seeking a refined and practical open-top grand tourer.
