BMW offers all the benefits of a soft roof versus a collapsible metal roof in terms of design, package dimensions, and weight. At the same time innovative ideas serve to minimize the inherent disadvantages of a softtop, particularly in terms of soundproofing and thermal insulation.

Fin look with the roof open and closed

Featuring fin softtop technology for the first time in automobile production, the new Convertible comes with the same dynamic contours as the 6 Series Coupé. And to provide the same characteristic, smooth line from the roof to the rear end of the car, the C-pillars are appropriately wide, creating this special concept of "fins". A further  side-effect of this design concept is that this is the first convertible in the world with that typical "Hofmeister kick", the design element in the rear side window so characteristic of BMW. Further attention to detail is borne out by the shaft strip on the rear side window split into two pieces to precisely continue the color of the roof at the end of the "Hofmeister kick" into part of the shaft trim.

Repeating the design and look of the fins in the form of plastic trim on the roof compartment, the new 6 Series Convertible retains its characteristic look even with the roof open. To match the color of the interior, this cover comes in either Basalt gray or Black. Through its color, shape and style, it perfectly rounds off the flowing lines of the interior with its harmonious and dynamic design.

The roof folds neatly yielding an extra-large luggage compartment

The roof structure made of steel bars proves the superior strength and solidity of the 6 Series Convertible. The most significant advantage of this steel structure, however, is its compact dimension. For although the roof has to cover a relatively long passenger compartment from the windscreen to the rear window, it folds up into a very compact package providing extra space for a luggage compartment very large for a convertible. A collapsible metal roof, by contrast, takes up much more space when folded.

This benefit is also attributable to the plastic trim on the roof cover serving not only to ensure good looks, but also providing superior function. Surrounded by PUR foam plastic, the LFI (long-fiber injection) molded element is hollow inside and therefore forms the upper edge on the roof compartment.

Vertical rear window between the fins

A conventional window at the rear would have taken up a great deal of space and capacity, since such a glass window integrated in the softtop would have been very large due to the shallow rake of the roof, with a corresponding reduction of luggage compartment capacity when driving with the roof down. And at the same time visibility to the rear would have been significantly impaired, since the tightening bracket on a conventional roof extending from one side to the other would have seriously obstructed the open line of vision available.

Now the fin structure makes such a tightening bracket superfluous. And instead of a huge flat window at the rear, the 6 Series Convertible comes with a vertical window hardly taking up any space in the luggage compartment while at the same time, despite its far more compact dimensions, offering the driver much better visibility to the rear. Yet a further advantage is that this vertical rear window is fully independent of the roof structure and bars, and may be moved up and down by itself, regardless of whether the roof is open or closed.

Unique air extraction ensuring a perfect climate inside the car

With the softtop closed the glass window between the roof fins allows a unique special comfort function. The rear window moves up and down electrically between the luggage compartment and the rear bulkhead, retracting fully into the body for effective, draught-free ventilation of the interior. The effect is at least as good as with a sliding roof on a fixed head coupé, and when it comes to driving noise this structure is even quieter and more efficient.

Contrary to common opinion, driving with the roof down on a very hot day is not necessarily advisable, since sunglare is excessive and the car's occupants may easily suffer sunburn or even a heat stroke. By lowering the side and rear windows, however, the driver and occupants of the new 6 Series Convertible can still take in all the fresh air they want - almost like driving with the roof down, but at the same time well protected from the sun.

When driving with the roof down and with passengers in the rear, a further option is to leave the rear window standing upright to protect rear-seat passengers from draughts and air swirls. And another advantage of this very special rear window is that in winter the heated window de-ices much more quickly, since ice or snow are hardly able to rest and cling tight to the window due to its vertical position.

Low weight of the softtop benefits the car's driving dynamics

Another advantage of the softtop roof is its lower weight compared with a collapsible roof structure - especially on a car as dynamic as the BMW 6 Series. Extra weight not only impairs road performance in general, but also has a very negative effect since the roof, when opened, is stowed directly above the rear axle. With a soft roof, however, this extra load is so small that the 6 Series Convertible retains its ideal 50:50 load distribution typical of a BMW almost in full.

Ultra-modern technology for superior comfort

To give the softtop the same high standard as a collapsible roof cabrio (as well as a fixed-head coupé) in terms of acoustics and thermal insulation, the rubberized upper roof layer is wind- and water-tight and is backed up by PUR foam inside. This innovative polyurethane foam insulation is much more effective than a conventional layer of fleece, reducing wind noise by up to 3 dB (A).

The fully automatic power roof opens both by remote control and by means of a button in the instrument console. A total of six hydraulic cylinders performs the actual opening and closing movement on both the roof and the roof compartment lid. With the roof open, the roof compartment lid - made of special SMC plastic -  protects the softtop within the compartment with maximum efficiency, keeping out water and dirt.

The complete process of opening or closing the roof takes less than 25 seconds. Within this short period the rear window and all side windows are also retracted or moved up as required, and the softtop is fastened electrically on to the windscreen frame and, respectively, the roof lid.

Opening and closing the roof even while driving

Drivers often wish to use a short stop at the traffic lights to open or close the roof. And should the short time available ever be insufficient, the driver of the 6 Series Convertible need not worry, since he is able to start off all the same, continuing the process of opening or closing the roof up to a road speed of 30 km/h or 20 mph. Then, should the driver exceed this speed limit, he will be informed by a warning signal that the process of opening or closing the roof has not yet been concluded.

The 6 Series Convertible comes with a specially developed wind deflector as special equipment. Designed and optimized in the wind tunnel, this special equipment offers the driver and front passenger comfort in terms of draught-free motoring and open-air driving pleasure. Fitted above the rear seats, the wind deflector is conceived for use by the driver alone or with only one passenger at the front. Then, collapsing at two points, the deflector goes into a special bag taking up only very little space inside the luggage compartment.

The wind deflector itself is made of a fine-mesh net within a powder-coated aluminum profile frame fastened on to the body of the car by means of glass-fiber-reinforced plastic cornerpieces and hinges.

When driving with the roof down and with four passengers in the car, the vertical rear window offers the passengers at the rear a certain degree of protection from wind and draughts, although admittedly this cannot be compared with the superior protection provided by a full-size wind deflector.

Source: BMW AG

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