Webasto boss Franz-Josef Kortuem has asked Bernd Lieberoth-Leden, head of the niche car manufacturer Karmann, to comment on his concerns that the company's Hyundai CCS Concept Car infringed Webasto's patents.
The concept car was fitted with a retractable folding-sliding roof made of glass, which means the car can be used as a coupe, semi-open targa or as a convertible.
Kortuem believes that some of the elements used in the complicated roof design are trademarked by Webasto.
A Karmann spokesman said that it happens from time to time in the car industry that the wheel is invented a second time.
He added that the show car was only a study. Hyundai has not yet decided if the CCS will go into production.