BMW to Give M3 Cabriolet Regular Cloth Roof?

M Series (BMW) Photos

BMW is contemplating putting a soft cloth top over the cabin of the next M3. (Photo: BMW)

The roofing system is just too heavy for an M3, increasing the car's center of gravity. (Photo: BMW)

Would BMW be able to justify the cost in making the entire folding hardtop system out of carbon fiber, like the fixed roof of the M6? (Photos: BMW)

The final piece of the 3-Series puzzle, the 3-Series Cabriolet is ready for launch.It was a while in the making but the car, which made its international debut at the NAIAS in Detroit looks to be well worth the wait thanks to its folding hardtop roof, a first for BMW. But rumor has it that there are some big changes that will happen between the open roofed 3-Series and the up and coming 400-410 horsepower M3 Cabriolet (which has yet to be launched).

The issue that’s causing engineers and testers great grief is the roof system, which has its obvious ups and downs. Being made of metal as opposed to plastic or the traditional cloth, the roof as a whole is far heavier, which is not desirable in the slightest, considering the M3’s prerogative is to go fast. As it stands, the folding hardtop roof on the 3-Series Cabriolet weighs approximately 440 pounds.

The solution that BMW is considering is going back to a regular clothroof. Reports show that BMW is working on developing a cloth top that can withstand high operating speeds, plus offer better sound insulation from the outdoors. Luxury firms such as Audi and Saab offer “acoustically tuned” roof systems that are just as quiet as their hardtop sedan cousins, therefore we’d expect no less from BMW which usually strives for excellence. Besides scaling the portly gains by somewhere around 250 lbs, a fabric roof would also free up trunk space. This would add the 3-Series to the ranks of automobile manufacturers that offer both a folding hardtop and a regular convertible roof for consumers, though, unlike the Mazda MX-5 and Chrysler Sebring, this is more of a special case.

A further option that’s also under consideration is for BMW to keep the folding hardtop roof, but to make it out of a different material. BMW’s already shown its familiarity with carbon fiber on the roof of the M6 Coupe and the M3 CSL, although such an application with the M3 Cabriolet would mark a first for a folding hardtop convertible. It would certainly make those top-up 155 mph autobahn blasts easier on the ears, plus give the added sense of security in stormy weather, but at what cost? The plan would involve replacing each of the roof panels with one made of that strong woven stuff, plus the arms that raise and lower the roof into position. Keep in mind that the M6’s use of carbon fiber overhead only consists of the flat roof panels and not the side pillars. Think about how dear such an investment would be and you can already see its potential fading away.

In our opinion, we think that BMW, in its pursuit to deliver the best performance, will probably yield a soft top, though, in honesty we don’t think most buyers would care too much if the car was left with the 3-Series Cabriolet’s roof, sans modification. The advent of a new soft-top might also allow for a more bargain oriented 3-Series Cabriolet, leaving the folding hardtop for pricier models; a step that may be necessary to offset the costs allocated to a comparatively low volume vehicle.