Thanks to Eddypeck for his time and effort!
Zender is an aftermarket styling and accessories company, famed for sports performance, aerodynamic design and body kits.
Zender produced styling parts for VW.
Extract taken (and edited) from Zender website: http://www.zendergroup.com/en/ I don't think the German to English translation is it's best but I'm sure you get the idea.
At the start of the seventies, Zender had become a reference point in the sector of automotive design, and in 1974 Ford Werke AG and Volkswagen AG became Zender clients, thanks to new development technologies that permitted the production of aerodynamic parts for car bodies, made of the highest quality PUR-RIM and ABS materials.
Zender grew over the years and refined its production of accessories for automobiles. A large distribution network, which in 1977 covered more than 40 countries worldwide. A brand synonymous with quality and ingenuity, expressed in prototype cars, futuristic design and innovative technology.
Zender Industrieprodukte GmbH was founded in 1987, capable of meeting the increasing demands from the major car manufacturers. Everyone searching for a part that could make them stand out, everyone certain of finding in Zender that musician capable of making the strings of every instrument vibrate.
Over the years Zender has always had an eye for collaboration with car manufacturers, choosing locations close to them as bases for his own modification centres. For inexpensive and eco-friendly logistical support.
The OSV is founded in 2000, the same year as the Adam Opel AG. The company is located in Rüsselsheim and Bochum, the same site as the Opel factory where special gas vehicles are manufactured. Six years later Zender sells its own shares to the Adam Opel AG.
Zender was partner and shareholder of Opel until 2006, keeping a fruitful collaboration ongoing and providing jobs to 250 employees.