* Founders retain remaining shares
* Italdesign has sales of over 100 million euros a year
* No financial details given
TURIN, Italy, May 25 (Reuters) - German carmaker Volkswagen (VOWG.DE) said it was buying a 90.1 percent stake in Italian auto designer Italdesign, without giving any detail on price.
Volkswagen chief executive Martin Winterkorn said on Tuesday the purchase would be made through VW's Lamborghini sports car unit. The Giugiaro family will retain the remaining shares.
Giorgetto Giugiaro, who founded the design group with Aldo Mantovani in 1968, said Italdesign would have a "promising perspective" by joining Volkswagen.
Italdesign has annual sales of over 100 million euros ($122 million) and created the Golf I along with concepts for the first VW Passat, the Scirocco and the Audi 80.
Italdesign has also worked on models for dominant Italian carmaker Fiat FIA.MI, including the Fiat Punto and the Alfa Romeo 159. (Reporting by Gianni Montani, writing by Jo Winterbottom; Editing by Dan Lalor) ($1 = 0.8174 euro)