The BMW 6 Series Convertible (F12) 640i xDrive Steptronic, produced from 2013 to 2015, represents a compelling blend of luxury, performance, and all-weather capability within the F12 6 Series range. Positioned as a mid-range offering, it slotted between the entry-level 630i and the high-performance 650i models. This variant aimed to provide a refined grand touring experience with a potent engine and the added security of BMW’s xDrive all-wheel-drive system, coupled with the convenience of an eight-speed automatic transmission. The F12 generation itself was a successor to the E64 6 Series, aiming to recapture the spirit of the original 6 Series coupes and convertibles from the 1970s and 80s.
Technical Specifications
| Brand | BMW |
| Model | 6 Series |
| Generation | 6 Series Convertible (F12) |
| Type (Engine) | 640i (320 Hp) xDrive Steptronic |
| Start of production | 2013 |
| End of production | 2015 |
| Powertrain Architecture | Internal Combustion engine |
| Body type | Cabriolet |
| Seats | 4 |
| Doors | 2 |
| Fuel consumption (urban) | 11.2-11.4 l/100 km (21 – 20.6 US mpg, 25.2 – 24.8 UK mpg, 8.9 – 8.8 km/l) |
| Fuel consumption (extra urban) | 6.5-6.6 l/100 km (36.2 – 35.6 US mpg, 43.5 – 42.8 UK mpg, 15.4 – 15.2 km/l) |
| Fuel consumption (combined) | 8.2-8.4 l/100 km (28.7 – 28 US mpg, 34.4 – 33.6 UK mpg, 12.2 – 11.9 km/l) |
| CO2 emissions | 192-195 g/km |
| Fuel Type | Petrol (Gasoline) |
| Acceleration 0 – 100 km/h | 5.4 sec |
| Acceleration 0 – 62 mph | 5.4 sec |
| Acceleration 0 – 60 mph | 5.1 sec |
| Maximum speed | 250 km/h (155.34 mph) |
| Emission standard | Euro 6 |
| Weight-to-power ratio | 6 kg/Hp, 167.5 Hp/tonne |
| Weight-to-torque ratio | 4.2 kg/Nm, 235.6 Nm/tonne |
| Power | 320 Hp @ 5800-6000 rpm |
| Power per litre | 107.4 Hp/l |
| Torque | 450 Nm @ 1300-4500 rpm (331.9 lb.-ft. @ 1300-4500 rpm) |
| Engine layout | Front, Longitudinal |
| Engine Model/Code | N55B30A |
| Engine displacement | 2979 cm3 (181.79 cu. in.) |
| Number of cylinders | 6 |
| Engine configuration | Inline |
| Cylinder Bore | 84 mm (3.31 in.) |
| Piston Stroke | 89.6 mm (3.53 in.) |
| Compression ratio | 10.2:1 |
| 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) |
| Coolant | 9.3 l (9.83 US qt | 8.18 UK qt) |
| Kerb Weight | 1910 kg (4210.83 lbs.) |
| Max. weight | 2400 kg (5291.09 lbs.) |
| Max load | 490 kg (1080.27 lbs.) |
| Trunk (boot) space – minimum | 300 l (10.59 cu. ft.) |
| Trunk (boot) space – maximum | 350 l (12.36 cu. ft.) |
| Fuel tank capacity | 70 l (18.49 US gal | 15.4 UK gal) |
| Length | 4894 mm (192.68 in.) |
| Width | 1894 mm (74.57 in.) |
| Height | 1365 mm (53.74 in.) |
| Wheelbase | 2855 mm (112.4 in.) |
| Front track | 1600 mm (62.99 in.) |
| Rear (Back) track | 1665 mm (65.55 in.) |
| Ride height (ground clearance) | 123 mm (4.84 in.) |
| Drag coefficient (Cd) | 0.31 |
| Minimum turning circle (turning diameter) | 11.7 m (38.39 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 | 225/55 R17; 245/45 R18; 275/45 R18; 245/40 R19; 275/35 R19; 245/35 R20; 275/30 R20 |
| Wheel rims size | 8J x 17; 8J x 18; 9J x 18; 8.5J x 19; 9J x 19; 8.5J x 20; 9J x 20 |
Powertrain & Engine Architecture
The heart of the 640i xDrive is BMW’s N55B30A 3.0-liter inline-six engine. This engine is a highly refined example of BMW’s engineering prowess, featuring direct fuel injection, a twin-scroll turbocharger, and Double VANOS variable valve timing. The N55 engine is known for its smooth power delivery and responsiveness. The engine produces 320 horsepower at 5800-6000 rpm and 450 Nm (331.9 lb-ft) of torque between 1300 and 4500 rpm. This broad torque curve contributes to strong acceleration in real-world driving conditions. The engine is paired with BMW’s eight-speed Steptronic automatic transmission, which offers both fully automatic operation and manual gear selection via steering wheel-mounted paddles. The xDrive all-wheel-drive system intelligently distributes power between the front and rear axles, enhancing traction and stability, particularly in adverse weather conditions.
Driving Characteristics
The 640i xDrive Steptronic delivers a refined and capable driving experience. While not as overtly sporty as the 650i, it provides ample power for confident overtaking and cruising. The eight-speed automatic transmission is well-tuned, offering smooth and quick shifts. The xDrive system provides a secure and planted feel, inspiring confidence on both dry and wet roads. The gear ratios are optimized for a balance of acceleration and fuel efficiency. Compared to the 630i, the 640i offers a noticeable performance upgrade, while the xDrive system provides superior grip compared to rear-wheel-drive models. However, the added weight of the xDrive system does slightly impact agility compared to lighter variants.
Equipment & Trim Levels
The 640i xDrive typically came well-equipped as standard. Common features included leather upholstery, power-adjustable seats with memory function, a premium sound system, automatic climate control, and BMW’s iDrive infotainment system with a central display screen. Optional extras were plentiful, including features like active steering, adaptive suspension, a head-up display, and various driver assistance systems such as lane departure warning and blind-spot monitoring. Interior trim options included a variety of wood and aluminum finishes. The convertible top was fully automatic and could be raised or lowered in around 24 seconds.
Chassis & Braking
The F12 6 Series Convertible features a sophisticated chassis design. The front suspension utilizes a double-wishbone setup, while the rear employs an independent multi-link suspension. This configuration provides a comfortable ride while maintaining good handling characteristics. The 640i xDrive is equipped with ventilated disc brakes on all four wheels, providing ample stopping power. The ABS (Anti-lock Braking System) and Electronic Stability Control (ESC) systems further enhance safety. The steering is a rack-and-pinion system with electric power assistance, offering precise and responsive steering feel.
Market Reception & Comparison
The 640i xDrive was generally well-received by automotive critics. It was praised for its refined engine, comfortable ride, and all-weather capability. Some reviewers noted that it didn’t quite possess the outright sporting character of some of its rivals, but it offered a compelling blend of luxury and performance. Compared to the 650i, the 640i offered a more accessible price point and slightly better fuel economy. Against competitors like the Mercedes-Benz E-Class Cabriolet and the Audi A5 Cabriolet, the 640i xDrive held its own with its distinctive styling and engaging driving dynamics.
Legacy
The N55 engine, found in the 640i xDrive, has proven to be a relatively reliable powerplant when properly maintained. Common issues include oil leaks and occasional problems with the fuel injectors, but these are generally not catastrophic failures. The eight-speed Steptronic transmission is also known for its durability. Today, the F12 6 Series Convertible 640i xDrive represents a desirable entry point into the world of BMW luxury convertibles. Well-maintained examples continue to command reasonable prices on the used car market, appealing to buyers seeking a stylish and capable grand tourer.
