The BMW 8 Series Convertible (G14) 840i Steptronic, produced from July 2019 through 2020, represents a luxurious and performance-oriented offering within the G14 generation of BMW’s flagship convertible. Positioned as a mid-range variant within the 8 Series lineup, it slots between the base 840d and the high-performance M8 models. This variant aimed to deliver a balance of refined driving dynamics, sophisticated technology, and open-air enjoyment, appealing to buyers seeking a grand touring experience. The G14 840i utilizes BMW’s modern engineering principles, focusing on lightweight construction and advanced powertrain technology.
Technical Specifications
| Brand | BMW |
| Model | 8 Series |
| Generation | 8 Series Convertible (G14) |
| Type (Engine) | 840i (340 Hp) Steptronic |
| Start of production | July, 2019 |
| End of production | 2020 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Cabriolet |
| Seats | 4 |
| Doors | 2 |
| Fuel consumption (economy) – urban (NEDC) | 9.0-9.3 l/100 km (26.1 – 25.3 US mpg, 31.4 – 30.4 UK mpg, 11.1 – 10.8 km/l) |
| Fuel consumption (economy) – extra urban (NEDC) | 6.3-6.4 l/100 km (37.3 – 36.8 US mpg, 44.8 – 44.1 UK mpg, 15.9 – 15.6 km/l) |
| Fuel consumption (economy) – combined (NEDC) | 7.3-7.5 l/100 km (32.2 – 31.4 US mpg, 38.7 – 37.7 UK mpg, 13.7 – 13.3 km/l) |
| CO2 emissions (NEDC) | 165-170 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 5.3 sec |
| Acceleration 0 – 62 mph | 5.3 sec |
| Acceleration 0 – 60 mph | 5 sec (Calculated) |
| Maximum speed | 250 km/h (155.34 mph) |
| Emission standard | Euro 6d – TEMP |
| Weight-to-power ratio | 5.4 kg/Hp, 185.8 Hp/tonne |
| Weight-to-torque ratio | 3.7 kg/Nm, 273.2 Nm/tonne |
| Power | 340 Hp @ 5000-6500 rpm |
| Power per litre | 113.4 Hp/l |
| Torque | 500 Nm @ 1600-4500 rpm (368.78 lb.-ft. @ 1600-4500 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | B58B30C |
| Engine displacement | 2998 cm3 (182.95 cu. in.) |
| Number of cylinders | 6 |
| 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 |
| Engine oil capacity | 6.5 l (6.87 US qt | 5.72 UK qt) |
| Kerb Weight | 1830 kg (4034.46 lbs.) |
| Max. weight | 2340 kg (5158.82 lbs.) |
| Max load | 510 kg (1124.36 lbs.) |
| Trunk (boot) space – minimum | 280 l (9.89 cu. ft.) |
| Trunk (boot) space – maximum | 350 l (12.36 cu. ft.) |
| Fuel tank capacity | 68 l (17.96 US gal | 14.96 UK gal) |
| Length | 4843 mm (190.67 in.) |
| Width | 1902 mm (74.88 in.) |
| Width including mirrors | 2137 mm (84.13 in.) |
| Height | 1339 mm (52.72 in.) |
| Wheelbase | 2822 mm (111.1 in.) |
| Front track | 1627 mm (64.06 in.) |
| Rear (Back) track | 1642 mm (64.65 in.) |
| Ride height (ground clearance) | 118 mm (4.65 in.) |
| Drag coefficient (Cd) | 0.30 |
| Minimum turning circle | 11.6 m (38.06 ft.) |
| Drivetrain Architecture | 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 |
Powertrain & Engine Architecture
At the heart of the 840i Steptronic lies BMW’s B58B30C 3.0-liter inline-six engine. This engine is a member of BMW’s modular engine family, known for its smooth power delivery and efficiency. The B58 utilizes a single twin-scroll turbocharger, direct fuel injection, and Double-VANOS variable valve timing for both intake and exhaust. This combination results in a peak output of 340 horsepower at 5,000-6,500 rpm and 500 Nm (368 lb-ft) of torque available from a low 1,600 rpm to 4,500 rpm. The engine’s architecture emphasizes responsiveness and a broad torque curve, making it well-suited for both relaxed cruising and spirited driving. The engine is paired with BMW’s 8-speed Steptronic automatic transmission. This transmission features a torque converter and offers smooth, quick shifts. It also includes features like launch control and adaptive shift programs to optimize performance and efficiency based on driving style.
Driving Characteristics
The 840i Steptronic delivers a refined and engaging driving experience. The combination of the potent inline-six engine and the smooth-shifting 8-speed automatic results in brisk acceleration – 0 to 60 mph in approximately 5 seconds. While not as aggressively tuned as the M8, the 840i provides ample power for confident overtaking and enjoyable cruising. The automatic transmission is programmed to prioritize comfort in normal driving modes, but can be shifted manually via steering wheel-mounted paddles for more control. The rear-wheel-drive configuration contributes to a balanced feel, although traction control systems are essential to manage power delivery, especially in inclement weather. Compared to the 840d (diesel variant), the 840i offers a more responsive and rev-happy engine character, albeit with slightly lower fuel economy.
Equipment & Trim Levels
The 840i Steptronic came standard with a comprehensive array of luxury features. Interior appointments included 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 parking sensors. Optional extras included features like adaptive cruise control, a head-up display, upgraded leather options, and various interior trim packages. The convertible top was a fully automatic soft top, available in several colors, and designed for quiet operation at highway speeds.
Chassis & Braking
The 8 Series Convertible utilizes a lightweight chassis construction, incorporating aluminum and high-strength steel to minimize weight and maximize rigidity. The suspension system consists of a double-wishbone front axle and a multi-link rear axle, tuned for a balance of comfort and handling. The 840i is equipped with ventilated disc brakes on all four wheels, providing ample stopping power. Electronic stability control (ESC) and traction control systems are standard, 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 BMW 8 Series Convertible (G14) 840i Steptronic was generally well-received by automotive critics. Reviewers praised its luxurious interior, refined driving dynamics, and powerful engine. The automatic transmission was noted for its smoothness and responsiveness. Compared to competitors like the Mercedes-Benz S-Class Cabriolet and the Porsche 911 Cabriolet, the 840i offered a unique blend of grand touring comfort and sporty handling. Fuel economy was considered reasonable for a vehicle of its class, although the gasoline engine did not match the efficiency of the 840d diesel. Reliability reports have been generally positive, with few widespread issues reported.
Legacy
The B58 engine has proven to be a robust and reliable powerplant, and the 840i’s powertrain is expected to provide years of dependable service with proper maintenance. On the used car market, the G14 840i Steptronic holds its value well, appealing to buyers seeking a luxurious and capable convertible. Its combination of performance, comfort, and technology continues to make it a desirable option in the high-end convertible segment. The G14 generation 8 Series, including the 840i, represents a return to BMW’s grand touring roots, offering a sophisticated and engaging driving experience.
