The BMW 8 Series Convertible (G14) M850i xDrive Steptronic, produced from 2019 to 2020, represents the high-performance variant of the second-generation 8 Series. Positioned as the flagship convertible within the 8 Series lineup, the M850i combined luxurious appointments with potent power derived from BMW’s twin-turbocharged V8 engine and xDrive all-wheel-drive system. It aimed to deliver a grand touring experience with a focus on both comfort and exhilarating performance, competing with vehicles like the Porsche 911 Cabriolet and Mercedes-Benz S-Class Cabriolet.
Technical Specifications
| Brand | BMW |
| Model | 8 Series |
| Generation | 8 Series Convertible (G14) |
| Type | M850i (530 Hp) xDrive Steptronic |
| Start of production | 2019 |
| End of production | 2020 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Cabriolet |
| Seats | 4 |
| Doors | 2 |
| Fuel consumption (urban) | 13.3-13.6 l/100 km (17.7 – 17.3 US mpg, 21.2 – 20.8 UK mpg, 7.5 – 7.4 km/l) |
| Fuel consumption (extra urban) | 7.9-8.0 l/100 km (29.8 – 29.4 US mpg, 35.8 – 35.3 UK mpg, 12.7 – 12.5 km/l) |
| Fuel consumption (combined) | 9.9-10.0 l/100 km (23.8 – 23.5 US mpg, 28.5 – 28.2 UK mpg, 10.1 – 10 km/l) |
| CO2 emissions | 229-225 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 3.9 sec |
| Acceleration 0 – 62 mph | 3.9 sec |
| Acceleration 0 – 60 mph | 3.7 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Emission standard | Euro 6d-TEMP |
| Weight-to-power ratio | 3.8 kg/Hp, 263 Hp/tonne |
| Weight-to-torque ratio | 2.7 kg/Nm, 372.2 Nm/tonne |
| Power | 530 Hp @ 5500-6000 rpm |
| Power per litre | 120.6 Hp/l |
| Torque | 750 Nm @ 1800-4600 rpm (553.17 lb.-ft. @ 1800-4600 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | N63B44D |
| Engine displacement | 4395 cm3 (268.2 cu. in.) |
| Number of cylinders | 8 |
| Engine configuration | V-engine |
| Cylinder Bore | 89 mm (3.5 in.) |
| Piston Stroke | 88.3 mm (3.48 in.) |
| Compression ratio | 10.5:1 |
| Number of valves per cylinder | 4 |
| Fuel injection system | Direct injection |
| Engine aspiration | Twin-power turbo, Intercooler |
| Engine oil capacity | 10.5 l (11.1 US qt | 9.24 UK qt) |
| Coolant | 10.5 l (11.1 US qt | 9.24 UK qt) |
| Kerb Weight | 2015 kg (4442.31 lbs.) |
| Max. weight | 2515 kg (5544.63 lbs.) |
| Max load | 500 kg (1102.31 lbs.) |
| Trunk (boot) space – minimum | 350 l (12.36 cu. ft.) |
| Fuel tank capacity | 68 l (17.96 US gal | 14.96 UK gal) |
| Length | 4851 mm (190.98 in.) |
| Width | 1902 mm (74.88 in.) |
| Width including mirrors | 2137 mm (84.13 in.) |
| Height | 1345 mm (52.95 in.) |
| Wheelbase | 2822 mm (111.1 in.) |
| Front track | 1627 mm (64.06 in.) |
| Rear (Back) track | 1642 mm (64.65 in.) |
| Front overhang | 953 mm (37.52 in.) |
| Rear overhang | 1076 mm (42.36 in.) |
| Ride height (ground clearance) | 125 mm (4.92 in.) |
| Drag coefficient (Cd) | 0.32 |
| Minimum turning circle | 11.9 m (39.04 ft.) |
| Drive wheel | All wheel drive (4×4) |
| 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 | 245/35 R20 95Y; 275/30 R20 97Y |
| Wheel rims size | 8J x 20; 9J x 20 |
Powertrain & Engine Architecture
The heart of the M850i is BMW’s N63B44D 4.4-liter twin-turbocharged V8 engine. This engine, a member of the N63 family, utilizes direct fuel injection and Valvetronic variable valve timing to optimize both power and efficiency. The twin-scroll turbochargers are positioned within the V of the engine, contributing to a more compact design and improved responsiveness. The engine produces 530 horsepower at 5,500-6,000 rpm and a substantial 750 Nm (553 lb-ft) of torque between 1,800 and 4,600 rpm. This broad torque curve provides effortless acceleration in virtually any gear.
Power is transmitted to all four wheels via BMW’s xDrive all-wheel-drive system and an 8-speed Steptronic automatic transmission. The Steptronic transmission offers both fully automatic operation and manual gear selection via steering wheel-mounted paddles. The xDrive system is rear-biased, prioritizing power delivery to the rear wheels for a more engaging driving experience, while seamlessly distributing torque to the front wheels when traction is needed.
Driving Characteristics
The M850i Convertible delivers a remarkably refined yet potent driving experience. The combination of the powerful V8 engine, the quick-shifting Steptronic transmission, and the xDrive all-wheel-drive system results in blistering acceleration – 0 to 60 mph in approximately 3.7 seconds. The engine’s abundant torque makes overtaking effortless, and the transmission is programmed to provide smooth and decisive shifts. While the xDrive system enhances traction, it doesn’t entirely eliminate the possibility of oversteer, allowing for a degree of driver involvement. The convertible top, a soft-top design, can be raised or lowered in around 15 seconds at speeds up to 30 mph.
Equipment & Trim Levels
The M850i Convertible came standard with a comprehensive array of luxury and technology features. Standard equipment included leather upholstery, heated and ventilated front seats, a premium sound system (typically Bowers & Wilkins), a 12.3-inch digital instrument cluster, and a 10.25-inch central infotainment display with iDrive 7.0 operating system. Optional extras included a head-up display, gesture control, active roll stabilization, and various interior trim options. The M850i also featured BMW’s Driving Assistance Professional package, which included adaptive cruise control, lane keeping assist, and automatic parking assist.
Chassis & Braking
The G14 8 Series Convertible utilizes a sophisticated chassis design featuring a double-wishbone front suspension and an independent multi-link rear suspension. Adaptive dampers were standard, allowing drivers to adjust the suspension firmness to suit their preferences. The M850i was equipped with large, ventilated disc brakes at all four corners, providing ample stopping power. The braking system also included ABS, dynamic stability control, and corner brake control.
Market Reception & Comparison
The M850i Convertible was generally well-received by automotive critics. Praise was directed towards its powerful engine, luxurious interior, and refined driving dynamics. Some reviewers noted that the car’s size and weight could make it feel less agile than smaller sports cars. Compared to the 840i Convertible (equipped with a six-cylinder engine), the M850i offered significantly more power and performance, but at a higher price point. Fuel economy, while respectable for a vehicle of this type, was considerably lower than that of the 840i.
Legacy
The G14 M850i xDrive Steptronic represents a compelling blend of luxury and performance in the grand touring segment. While production was relatively short-lived, the model has established itself as a desirable used car. The N63 engine, while known for its complexity, has proven to be reasonably reliable when properly maintained. Common maintenance items include regular oil changes, spark plug replacements, and inspection of the cooling system. The M850i Convertible continues to appeal to buyers seeking a high-performance luxury convertible with a sophisticated driving experience.
