The BMW 4 Series Convertible (G23) 430i Steptronic, produced from 2020 through January 2024, represents BMW’s mid-range offering in the fourth generation of the 4 Series convertible. Positioned as a balance between performance and comfort, the 430i aimed to provide an engaging driving experience without the higher price point and more aggressive tuning of the M440i. It slots into the lineup as a step up from the 420i, offering significantly more power and a more refined driving experience. The G23 chassis debuted as a replacement for the F33 generation, incorporating updated technology and styling cues consistent with the broader BMW design language of the period.
Technical Specifications
| Brand | BMW |
| Model | 4 Series |
| Generation | 4 Series Convertible (G23) |
| Type (Engine) | 430i (258 Hp) Steptronic |
| Start of production | 2020 |
| End of production | January, 2024 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Cabriolet |
| Seats | 4 |
| Doors | 2 |
| Combined fuel consumption (WLTP) | 6.9-7.7 l/100 km (34.1 – 30.5 US mpg, 40.9 – 36.7 UK mpg, 14.5 – 13 km/l) |
| CO2 emissions (WLTP) | 158-176 g/km |
| Fuel consumption (economy) – urban (NEDC) | 7.5-7.8 l/100 km (31.4 – 30.2 US mpg, 37.7 – 36.2 UK mpg, 13.3 – 12.8 km/l) |
| Fuel consumption (economy) – extra urban (NEDC) | 5.2-5.6 l/100 km (45.2 – 42 US mpg, 54.3 – 50.4 UK mpg, 19.2 – 17.9 km/l) |
| Fuel consumption (economy) – combined (NEDC) | 6.0-6.4 l/100 km (39.2 – 36.8 US mpg, 47.1 – 44.1 UK mpg, 16.7 – 15.6 km/l) |
| CO2 emissions (NEDC) | 138-147 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 6.2 sec |
| Acceleration 0 – 62 mph | 6.2 sec |
| Acceleration 0 – 60 mph | 5.9 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Emission standard | Euro 6d |
| Weight-to-power ratio | 6.6 kg/Hp, 150.4 Hp/tonne |
| Weight-to-torque ratio | 4.3 kg/Nm, 233.2 Nm/tonne |
| Power | 258 Hp @ 5000-6500 rpm |
| Power per litre | 129.1 Hp/l |
| Torque | 400 Nm @ 1550-4400 rpm (295.02 lb.-ft. @ 1550-4400 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B48B20B |
| Engine displacement | 1998 cm3 (121.93 cu. in.) |
| Number of cylinders | 4 |
| 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 | VALVETRONIC |
| Engine oil capacity | 5.25 l (5.55 US qt | 4.62 UK qt) |
| Coolant | 9.8 l (10.36 US qt | 8.62 UK qt) |
| Kerb Weight | 1715 kg (3780.93 lbs.) |
| Max. weight | 2200 kg (4850.17 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%) | 1600 kg (3527.4 lbs.) |
| Permitted trailer load without brakes | 750 kg (1653.47 lbs.) |
| Permitted towbar download | 75 kg (165.35 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 | 1575 mm (62.01 in.) |
| Rear (Back) track | 1611 mm (63.43 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 (turning diameter) | 11.4 m (37.4 ft.) |
| Drivetrain Architecture | The Internal combustion engine (ICE) drives the rear wheels of the vehicle. |
| Drive wheel | Rear wheel drive |
| Number of gears and type of gearbox | 8 gears, automatic transmission Steptronic |
| Front suspension | Double wishbone |
| Rear suspension | Independent multi-link suspension |
| 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 | 225/50 R17 98Y XL |
| Wheel rims size | 7.5J x 17 |
Powertrain & Engine Architecture
The 430i Steptronic is powered by BMW’s B48B20B 2.0-liter inline-four cylinder engine. This engine is a member of BMW’s modular engine family, known for its efficiency and performance. The B48 utilizes a single, twin-scroll turbocharger with an intercooler, direct fuel injection, and BMW’s VALVETRONIC variable valve timing and lift system. VALVETRONIC allows for precise control of valve timing and lift, optimizing engine performance and fuel efficiency across a wide range of operating conditions. The engine produces 258 horsepower at 5000-6500 rpm and 295 lb-ft of torque between 1550-4400 rpm. The engine is longitudinally mounted, driving the rear wheels. The “Steptronic” designation refers to BMW’s 8-speed automatic transmission, known for its smooth shifts and responsiveness. This transmission features a torque converter and allows for both automatic and manual gear selection via steering wheel-mounted paddles.
Driving Characteristics
The 430i Steptronic offers a comfortable and engaging driving experience. While not as overtly sporty as the M440i, the 2.0-liter turbo engine provides ample power for everyday driving and spirited acceleration. The 8-speed automatic transmission is well-tuned, providing smooth and quick shifts. The gear ratios are optimized for both fuel efficiency and performance, with a relatively tall final drive contributing to highway cruising comfort. Compared to a manual transmission equipped 430i, the Steptronic offers a more relaxed driving experience, particularly in stop-and-go traffic. However, some enthusiasts may find the automatic transmission slightly less engaging than a manual. The rear-wheel-drive configuration contributes to a balanced chassis and predictable handling.
Equipment & Trim Levels
The 430i Steptronic came standard with a comprehensive list of features, including BMW’s iDrive infotainment system with a 12.3-inch touchscreen display, navigation, Apple CarPlay and Android Auto compatibility, a premium sound system, leatherette upholstery, and automatic climate control. Available options included upgraded leather upholstery, a head-up display, a panoramic sunroof, adaptive suspension, and various driver-assistance systems such as lane departure warning and blind-spot monitoring. Exterior options included a variety of wheel designs, paint colors, and aerodynamic enhancements.
Chassis & Braking
The G23 4 Series Convertible utilizes a sophisticated chassis design featuring a double-wishbone front suspension and an independent multi-link rear suspension. This setup provides a good balance of ride comfort and handling precision. The 430i is equipped with ventilated disc brakes on all four wheels, providing ample stopping power. The electronic stability control (ESC) system helps to maintain control during challenging driving conditions. The steering is an electric power-assisted rack-and-pinion system, offering precise and responsive steering feel.
Market Reception & Comparison
The 430i Steptronic was generally well-received by automotive critics. It was praised for its refined engine, comfortable ride, and well-appointed interior. Critics noted that the 430i offered a good balance of performance and luxury, making it a compelling alternative to competitors such as the Audi A5 Cabriolet and Mercedes-Benz C-Class Cabriolet. Compared to the 420i, the 430i offered a significant performance upgrade, while remaining more affordable than the M440i. Fuel economy was considered respectable for a performance convertible, with combined fuel consumption figures ranging from 6.9 to 7.7 liters per 100 kilometers.
Legacy
The BMW 4 Series Convertible (G23) 430i Steptronic has proven to be a reliable and desirable used car. The B48 engine is known for its durability, and the 8-speed automatic transmission is generally trouble-free. Regular maintenance, including oil changes and fluid checks, is essential to ensure long-term reliability. The G23 generation represents a significant step forward in terms of technology and refinement compared to its predecessor, making it a popular choice among buyers looking for a stylish and capable convertible.
