French automaker Peugeot has turned the retractable hardtop convertible into a mainstream car with the help of 206 CC.
Since it was introduced in 2000, Peugeot has sold 325,000 units of the coupe-cabriolet with its roof system from French coachbuilder Heuliez.
That's fitting because Peugeot pioneered the retractable hardtop in 1934, but only sold a few dozen. In 1957, Ford introduced a two-piece folding hardtop convertible called the Skyliner for the US market and sold 50,000 over three years.
But a series of drawbacks, including cost, storage space, reliability and durability, kept automakers from using folding hardtops for decades.
The concept was re-introduced in the mid–1990s on the Mercedes-Benz SLK, which was co-developed by Mercedes-Benz and German coachbuilder Karmann. But folding hardtops at first were limited to premium cars that could stand the system's higher manufacturing costs.
Then the Peugeot 206 CC arrived, proving that consumers would buy mass-market hardtop convertibles. The 206 CC's breakthrough also forced all European volume-brand automakers to consider offering hardtop convertible variants for nearly every small and medium-sized platform they have developed.
The field is full of coachbuilders and convertible-top specialists offering retractable hardtops. And they are developing new technology to broaden the appeal and capabilities of convertible hardtops.
Germany's Car Top Systems (CTS), a wholly owned subsidiary of Porsche, is the largest supplier of retractable hardtops. CTS provides systems to the Mercedes SLK and SL and the Peugeot 307 CC.
CTS' two main rivals are France's Heuliez and Karmann of Germany. But competition in the field of roof system suppliers is building: Webasto's Oasys subsidiary and Edscha are becoming formidable hardtop players with new designs and technologies.
Since Mercedes' and Peugeot's hardtop introductions, everyone has used much the same approach and applied it to relatively small cars.
Those hardtops are two-piece roofs that fold into a clamshell shape -- the rounded exterior on the outside and interior sections inside -- and stow in the trunk with the help of electric motors.
All competitors have addressed the quality and reliability issues of hardtops and tackled other technical problems.
"We have developed a second-generation sensor switch that not only has a on-off mode but also can detect the top's position during the open-close operation," said Heuliez CEO Paul Queveau. "It has made the top faster and more reliable."
The system also automatically lowers the side windows whenever operating the top and raises them after the top is up.
"That improves water and air management because the windows [fit] better into the rubber seals," Queveau said.
When automakers remove fixed roofs from unibody structures designed so every portion of the body is a structural member, the car flexes more. With softtop convertibles, the top is also flexible and will work even if the body is only lightly modified to make it more rigid.
Hardtop convertibles require more rigidity so the metal top's panels will fit. But the requirement is not a hardship for automakers because stiffness makes a car feel higher quality to drivers, said Thomas Schütt, managing director of Webasto's subsidiary Oasys.
"The market requires more stiffness for better comfort anyway, both with the roof stowed in luggage compartment, or with the roof up," he said.
Karmann produces the folding hardtop for the Nissan Micra C+C.
Heuliez considered this in developing its production process for the new, two-seat Opel Tigra TwinTop.
"For better fit and to reduce adjustments once the roof system has been fitted to the car, we mount the module when the car is on its wheels, not on the conveyor belt," Queveau said.
But this assembly procedure is not exclusive to Heuliez. Karmann, the hardtop system supplier for the Nissan Micra C+C, does it the same way.
Karmann has set up a roof system production line for the Micra C+C inside Nissan's assembly plant in Sunderland, England.
Most of the other retractable hardtop suppliers either make their coupe-cabriolet models in their own factories or have plants near their customers.
CTS has a hardtop-making factory in Bremen, Germany, for the Mercedes SL and SLK, as well as a facility 80km from Peugeot's Sochaux, France, plant where the 307 CC is made.
Webasto is building a factory in a supplier park near VW's Autoeuropa assembly plant in Setubal, Portugal, that will supply the folding glass hardtop system for the Volkswagen Concept C.
VW will start production of the four-seat cabriolet in early 2006.
Karmann ships retractable hardtop systems for the Renault Megane coupe cabriolet from Germany to France.
For cost reasons, most hardtops are made of high-tensile steel. Usually only premium models use aluminum or composite materials, which weigh less. One exception is that Oasys uses aluminum for the Daihatsu Copen coupe convertible from Japan.