The BMW 4 Series Gran Coupe (G26 LCI), specifically the 420d variant with 190 horsepower and the Steptronic automatic transmission, represents a mid-cycle refresh of the G26 generation introduced in July 2024. Positioned as a stylish and practical four-door coupe, the 420d Mild Hybrid aims to balance fuel efficiency with respectable performance within the 4 Series lineup. This model builds upon the foundation of the G26 platform, shared with the 3 Series sedan and other BMW models, offering a more emotionally driven design compared to its more pragmatic sibling. The “LCI” (Life Cycle Impulse) facelift brings updated styling, enhanced technology, and refinements to the powertrain.
Technical Specifications
| Brand | BMW |
| Model | 4 Series |
| Generation | 4 Series Gran Coupe (G26 LCI, facelift 2024) |
| Type (Engine) | 420d (190 Hp) Mild Hybrid Steptronic |
| Start of production | July, 2024 |
| Powertrain Architecture | MHEV (Mild Hybrid Electric Vehicle) |
| Body type | Coupe |
| Seats | 5 |
| Doors | 5 |
| Combined fuel consumption (WLTP) | 5-5.6 l/100 km (47 – 42 US mpg, 56.5 – 50.4 UK mpg, 20 – 17.9 km/l) |
| CO2 emissions (WLTP) | 131-146 g/km |
| Fuel Type | Diesel |
| Acceleration 0 – 100 km/h | 7.3 sec |
| Acceleration 0 – 62 mph | 7.3 sec |
| Acceleration 0 – 60 mph | 6.9 sec |
| Maximum speed | 235 km/h (146.02 mph) |
| Emission standard | Euro 6e |
| Weight-to-power ratio | 9 kg/Hp, 111.4 Hp/tonne |
| Weight-to-torque ratio | 4.3 kg/Nm, 234.6 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 | 190 Hp @ 4000 rpm |
| Torque | 400 Nm @ 1750-2500 rpm (295.02 lb.-ft. @ 1750-2500 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B47D20B |
| Engine displacement | 1995 cm3 (121.74 cu. in.) |
| Number of cylinders | 4 |
| Engine configuration | Inline |
| Cylinder Bore | 84 mm (3.31 in.) |
| Piston Stroke | 90 mm (3.54 in.) |
| Compression ratio | 16.5:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Diesel Commonrail |
| Engine aspiration | Twin-power turbo, Intercooler |
| Valvetrain | DOHC |
| Engine oil capacity | 5.5 l (5.81 US qt | 4.84 UK qt) |
| Kerb Weight | 1705 kg (3758.88 lbs.) |
| Max. weight | 2260 kg (4982.45 lbs.) |
| Max load | 555 kg (1223.57 lbs.) |
| Trunk (boot) space – minimum | 470 l (16.6 cu. ft.) |
| Trunk (boot) space – maximum | 1290 l (45.56 cu. ft.) |
| Fuel tank capacity | 59 l (15.59 US gal | 12.98 UK gal) |
| Max. roof load | 75 kg (165.35 lbs.) |
| 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 | 4783 mm (188.31 in.) |
| Width | 1852 mm (72.91 in.) |
| Width including mirrors | 2073 mm (81.61 in.) |
| Height | 1442 mm (56.77 in.) |
| Wheelbase | 2856 mm (112.44 in.) |
| Front track | 1595 mm (62.8 in.) |
| Rear (Back) track | 1623 mm (63.9 in.) |
| Front overhang | 862 mm (33.94 in.) |
| Rear overhang | 1065 mm (41.93 in.) |
| Ride height (ground clearance) | 140 mm (5.51 in.) |
| Drag coefficient (Cd) | 0.26 |
| Minimum turning circle (turning diameter) | 12 m (39.37 ft.) |
| Drivetrain Architecture | Rear wheel drive. MHEV. ICE and electric motor drive the rear wheels. |
| 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 | 225/55 R17 |
| Wheel rims size | 7.5J x 17 |
INTRODUCTION
The BMW 420d Gran Coupe (G26 LCI) represents a compelling entry point into the 4 Series range. Introduced in July 2024, this variant combines a 2.0-liter turbocharged diesel engine with a 48-volt mild-hybrid system and an eight-speed Steptronic automatic transmission. The G26 LCI facelift brought subtle but significant changes to the exterior styling, interior technology, and engine refinement. This model is aimed at buyers seeking a blend of practicality, efficiency, and the BMW driving experience in a stylish package. It sits below the more powerful 430d and M440i models in the lineup, offering a more accessible price point.
Powertrain & Engine Architecture
At the heart of the 420d is the BMW B47D20B, a 2.0-liter inline-four cylinder diesel engine. This engine utilizes a common-rail direct injection system, delivering fuel at extremely high pressure for optimized combustion. The B47 engine is known for its robust construction and efficiency. The addition of a 48V mild-hybrid system provides a small power boost during acceleration and allows for smoother start-stop operation, improving fuel economy. The turbocharger is a twin-scroll unit, minimizing turbo lag and providing a more responsive driving experience. The eight-speed Steptronic automatic transmission is a torque-converter type, offering smooth and quick shifts. It’s programmed to adapt to the driver’s style and road conditions, and includes features like launch control and shift paddles for manual control.
Driving Characteristics
The 420d Gran Coupe delivers a comfortable and refined driving experience. While not as overtly sporty as its higher-powered siblings, the 190 hp and 400 Nm (295 lb-ft) of torque provide ample power for everyday driving and highway cruising. Acceleration from 0-60 mph takes approximately 6.9 seconds. The Steptronic transmission is well-matched to the engine, providing seamless gear changes. The mild-hybrid system contributes to a smoother and more responsive feel, particularly during initial acceleration. Compared to a manual transmission version (if offered), the automatic prioritizes ease of use and comfort over outright driver engagement. The rear-wheel-drive configuration contributes to balanced handling, although it can be less forgiving in slippery conditions than an all-wheel-drive system.
Equipment & Trim Levels
The 420d Gran Coupe typically comes well-equipped as standard. Key features include BMW’s iDrive infotainment system with a touchscreen display, navigation, Apple CarPlay and Android Auto compatibility, automatic climate control, and a suite of driver-assistance systems such as lane departure warning and forward collision warning. Interior upholstery is typically a combination of leatherette and cloth, with optional full leather upgrades available. Common optional extras include a premium sound system, a head-up display, adaptive suspension, and a panoramic sunroof. Trim levels often vary by market, but generally offer packages that bundle popular options together.
Chassis & Braking
The G26 Gran Coupe utilizes a sophisticated chassis design. The front suspension features a spring strut setup with a transverse stabilizer bar, while the rear employs an independent multi-link suspension, also with a stabilizer bar. This configuration provides a good balance between comfort and handling. Brakes are ventilated discs all around, providing ample stopping power. The standard ABS (Anti-lock Braking System) and electronic stability control enhance safety. The steering is an electric power-assisted rack and pinion system, offering precise and responsive control.
Market Reception & Comparison
The 420d Gran Coupe has generally been well-received by automotive critics as a practical and efficient option within the 4 Series range. It’s praised for its comfortable ride, refined engine, and stylish design. Compared to the 430d, the 420d offers lower running costs but sacrifices some performance. The 420d’s fuel economy is a key selling point, typically achieving between 47 and 56 mpg (UK combined cycle). Reliability has been generally good, although diesel particulate filter (DPF) issues can occur with frequent short journeys.
Legacy
The B47 engine family has proven to be a reliable and durable powertrain. The addition of the 48V mild-hybrid system in the LCI model is expected to further enhance its efficiency and longevity. On the used car market, the 420d Gran Coupe is likely to hold its value well due to its blend of practicality, style, and fuel efficiency. Regular maintenance, including timely servicing and DPF regeneration, will be crucial to ensuring the long-term reliability of this powertrain.
