The BMW 4 Series Convertible (G23) received a Life Cycle Impulse (LCI), or facelift, in March 2024. The 420i Steptronic variant, powered by a 2.0-liter turbocharged four-cylinder engine producing 184 horsepower, represents the entry point into the 4 Series Convertible range. Positioned as a more accessible option, it caters to buyers prioritizing a blend of style, comfort, and reasonable running costs over outright performance. This model builds upon the G23 platform, introduced in 2020, which aimed to deliver a more dynamic and refined open-top experience compared to its predecessor, the 3 Series Convertible.
Technical Specifications
| Brand | BMW |
| Model | 4 Series |
| Generation | 4 Series Convertible (G23 LCI, facelift 2024) |
| Type (Engine) | 420i (184 Hp) Steptronic |
| Start of production | March, 2024 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Cabriolet |
| Seats | 4 |
| Doors | 2 |
| Combined fuel consumption (WLTP) | 6.7-7.4 l/100 km (35.1 – 31.8 US mpg, 42.2 – 38.2 UK mpg, 14.9 – 13.5 km/l) |
| CO2 emissions (WLTP) | 152-169 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 8.2 sec |
| Acceleration 0 – 62 mph | 8.2 sec |
| Acceleration 0 – 60 mph | 7.8 sec |
| Maximum speed | 236 km/h (146.64 mph) |
| Emission standard | Euro 6e |
| Weight-to-power ratio | 9.2 kg/Hp, 108.9 Hp/tonne |
| Weight-to-torque ratio | 5.6 kg/Nm, 177.5 Nm/tonne |
| Power | 184 Hp @ 5000-6500 rpm |
| Power per litre | 92.1 Hp/l |
| Torque | 300 Nm @ 1350-4000 rpm (221.27 lb.-ft. @ 1350-4000 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B48 |
| 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 | 11:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Direct injection |
| Engine aspiration | Twin-power turbo, Intercooler |
| Valvetrain | Double-VANOS, VALVETRONIC |
| Engine oil capacity | 5.25 l (5.55 US qt | 4.62 UK qt) |
| Kerb Weight | 1690 kg (3725.81 lbs.) |
| Max. weight | 2185 kg (4817.1 lbs.) |
| Max load | 495 kg (1091.29 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 | 1573 mm (61.93 in.) |
| Rear (Back) 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 (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 | 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 | 225/50 R17 |
| Wheel rims size | 7.5J x 17 |
INTRODUCTION
The 2024 BMW 420i Convertible Steptronic represents a key offering within the G23 LCI (Life Cycle Impulse) range. Introduced in March 2024, this variant combines the open-air enjoyment of a convertible with a relatively efficient and accessible powertrain. It’s designed to appeal to drivers seeking a stylish and comfortable grand tourer, rather than a focused sports car. The G23 generation, built on the 1HX0/A3 platform shared with other BMW models, aimed to improve upon the previous 3 Series Convertible in terms of rigidity, handling, and overall refinement.
Powertrain & Engine Architecture
At the heart of the 420i Convertible lies the BMW B48 2.0-liter inline-four cylinder engine. This engine utilizes direct fuel injection and is equipped with a twin-scroll turbocharger, along with BMW’s VALVETRONIC variable valve timing and Double-VANOS variable camshaft timing systems. These technologies work in concert to optimize power delivery, fuel efficiency, and emissions. The engine produces 184 horsepower at 5000-6500 rpm and 300 Nm (221 lb-ft) of torque between 1350 and 4000 rpm. The ‘Steptronic’ transmission is an 8-speed automatic gearbox, known for its smooth shifts and responsiveness. It features a torque converter and allows for both automatic and manual gear selection via steering wheel-mounted paddles. The engine also incorporates a particulate filter to reduce emissions, meeting Euro 6e standards.
Driving Characteristics
The 420i Steptronic offers a comfortable and refined driving experience. While not as overtly sporty as higher-powered 4 Series variants, it provides adequate performance for everyday driving and cruising. The 0-60 mph acceleration time of around 7.8 seconds is respectable, and the broad torque curve ensures effortless overtaking. The 8-speed automatic transmission is well-matched to the engine, providing smooth and timely gear changes. Compared to a manual transmission, the Steptronic prioritizes convenience and ease of use, but may slightly diminish driver engagement. The rear-wheel-drive configuration contributes to balanced handling, although it can be less forgiving in adverse weather conditions than all-wheel-drive alternatives.
Equipment & Trim Levels
The 420i Convertible typically comes standard with features such as BMW’s iDrive infotainment system with a touchscreen display, automatic climate control, leatherette upholstery, and a suite of driver-assistance systems including lane departure warning and collision warning. Optional extras include premium leather upholstery, a Harman Kardon sound system, adaptive suspension, and a head-up display. The LCI facelift brought updated interior trim options and enhanced connectivity features. Specific trim levels (such as Sport, Luxury, or M Sport) could be added, offering different styling cues and additional equipment.
Chassis & Braking
The G23 4 Series Convertible features a robust chassis designed to maximize rigidity despite the absence of a fixed roof. The front suspension utilizes a spring strut design with a transverse stabilizer, while the rear employs an independent multi-link setup, also with a stabilizer bar. This configuration aims to provide a balance between comfort and handling. Braking duties are handled by ventilated disc brakes on all four wheels, providing ample stopping power. ABS (Anti-lock Braking System) is standard, enhancing safety and control during emergency braking situations. The suspension tuning is geared towards comfort, prioritizing a smooth ride over aggressive cornering.
Market Reception & Comparison
The 420i Convertible Steptronic was generally well-received by automotive critics as a capable and comfortable entry-level option. It was praised for its stylish design, refined interior, and smooth powertrain. However, some reviewers noted that the 184 horsepower engine could feel somewhat underpowered, particularly when fully loaded or tackling steep inclines. Compared to the more potent 430i and M440i variants, the 420i offers a more affordable price point but sacrifices some performance. In terms of fuel economy, the 420i generally achieves better figures than its higher-powered siblings, making it a more economical choice for drivers covering long distances. Reliability reports suggest the B48 engine is generally robust, but regular maintenance is crucial.
Legacy
The BMW B48 engine has proven to be a reliable and versatile powerplant, finding its way into numerous BMW models. The combination of this engine with the 8-speed Steptronic transmission has become a popular choice for drivers seeking a balance of performance, efficiency, and comfort. On the used car market, the 2024 420i Convertible Steptronic is expected to hold its value reasonably well, particularly examples with low mileage and a comprehensive service history. Its blend of style, practicality, and relatively low running costs should ensure continued demand among buyers seeking a premium open-top experience.
