Available in just two models, 840d (320bhp diesel), or 850i (530bhp petrol), reports Iain Robertson, the latest BMW 8-Series convertible marries elegance with sporting prowess in a display of premium-priced luxury, fine build quality and high performance.
With an exterior length of 4.8m, a width of 1.9m and height of 1.3m, the dimensions of the drop-top match almost exactly those of the BMW 8-Series coupé. BMW has focused on exceptional body rigidity for the new model, which ensures that only a small number of additional convertible-specific and weight-increasing measures were required in its construction.
The BMW 8-Series convertible cuts an impressive dash, with the roof either up, or down. Character lines trace the path of the airflow between the front and rear wheels, while tapered surfaces around the front wheels and doors spread out at the tops of the rear wheels. Discreet contouring marks out the surfacing above them, as the flanks transition into the rear end of the body. It is an impossibly handsome machine.
The compartment for the soft-top roof demands that the trailing edge of the car’s body is slightly higher than that of the coupé, although it still manages to appear extremely flat and hunkered to the road surface. So many droptops suffer from fits of unbearable ugliness, once their tops are lowered but there is none of that odd swagger to the 8-Series. In addition, horizontal lines and the light units extending into the flanks accentuate the width of the car. The high-level brake light embedded in the boot-lid adds to the low-slung look. Other model-specific features include a brace of contour lines on the boot, while the L-shaped tail-lights are underscored by the line of the taillight bar that illuminates across its width. Twin trapezoidal exhaust tailpipes round off the lower section of the rear apron.
The 8-Series convertible is equipped with adaptive LED headlights as standard, although BMW’s Laserlight development, with variable road illumination and selective beam operation, is available as a high-cost option. The car can be customised further, with the Chrome Line, or M Carbon exterior packages. The roof is both lightweight and provides additional acoustic insulation. Opening and closing automatically, in 18 seconds, at the touch of a button, it can be activated when the car is travelling at speeds of up to 31mph, which might be useful when driving in drizzle on the Cote d’Azur.
When the soft-top roof is erected, it sits taut over the interior, thus retaining its coupé-like silhouette, without compromising the car’s outline. Finished in black as standard, or in Anthracite Silver effect as a cost option, the soft-top stows away neatly beneath an in-built tonneau cover. In keeping with the rest of the car, it is finished in colours that complement and match the instrument panel and interior door/side panel trim and features eye-catching domes behind the rear seats.
The rear-seat backrest of the convertible model can be split 50:50 and, thanks to the through-loading facility, the capacity of the luggage compartment can be extended on demand. With the soft-top closed, the stowage capacity is 350-litres.
As mentioned earlier, the performance is excellent, with the petrol despatching 0-60mph in 3.6s (4.9s diesel) to a restricted top speed of 155mph. On the obverse side of the coin, up to 39.8mpg is possible from the diesel (26.6mpg petrol) and list prices (pre-discount) are £83,295 (840d) and £107,100 (850i). Considering that the diesel is not so far behind the petrol in performance terms, a saving of almost £24k might be worth contemplating.
The racing know-how retained by BMW’s Motorsport department was used for detailed modifications and enhancements on the convertible’s chassis, as well as the overall set-up to optimise the body’s torsional rigidity and ensure that the car delivers total driving pleasure, while having the ability to transport up to four occupants in consummate luxury. Adaptive M suspension with electronically controlled dampers is standard, as is BMW’s Integral Active Steering (IAS; on the 840d xDrive and M850i only), which is a system that angles the rear wheels slightly (at speeds of up to 45mph) to improve both overall agility, as well as reducing the turning circle slightly.
The damping characteristics can be adjusted via the Driving Experience Control (DEC) switch, located adjacent to the crystal-topped gear selector. SPORT and SPORT+ modes activate optimal responses for dynamic handling. They are discernibly different from the comfort-oriented damper settings in either ECO Pro, or COMFORT modes. In addition, active roll stabilisation, which improves ride quality, is available for the new BMW M850i xDrive convertible, as part of the optional Adaptive M suspension Professional package. The overall handling balance of the car is neutral, following BMW’s long held 50:50 weight distribution statement. However, there is sufficient power on tap in either version to kick the tail into oversteer on demand, should the traction control be switched off. Needless to say, all of the suspension enhancements mentioned are available at extra-cost.
All versions combine four-piston, fixed-calliper disc brakes at the front and single-piston, floating-calliper brakes at the rear. The electronic parking brake is operated by means of a button located on the centre console, the system being integrated into the rear brake callipers. The new BMW 840d xDrive convertible includes an M Sport braking system with 374mm discs; when specified with the optional M Technic Sport Package, the BMW 840d xDrive comes with 395mm brake discs (fitted to the BMW M850i xDrive as standard). Both versions of the M Sport braking system are recognisable by their blue callipers carrying the M logo.
The new convertible rides on 20.0-inch diameter M light-alloy wheels. These standard cast aluminium wheels in a grey metallic finish are clad in 245/35 R20 front and 275/30 R20 high-performance tyres at the rear. They have been specially developed for the BMW 8-Series models. Finally, a full complement of connectivity and driver aids feature in the convertible, with a large touch-screen in the centre-dash and a configurable instrument panel ahead of the driver.
Buying into class is part of the BMW remit and, while the 8-Series convertible is at the upper-end of the marque’s price range, high efficiency levels ensure that it could be a satisfyingly manageable prospect otherwise.