I first met Ferdinand Piech and Martin Winterkorn at the same time in Bobigny when I was R&D Director of Valeo Vision (Lighting). VW visited to learn more about Valeo; Piech and Winterkorn stayed half a day at Bobigny. Still now, I very well remeber the Piech's bright blue eyes fixed me while he asked technical questions on lighting with details I will have in mind all my life.
He asked me a lot of questions from my vision of lighting to a detailed question on the dimension of a particular lens. All this time, Winterkorn was behind Piech like a child behind his father.
A few years later I met again Winterkorn when he was Engineering Director of VW just before arriving at Audi as CEO. It was during the development of the headlamp for the VW Phaeton. He asked me to come with him, driving the car for an hour asking question after question to understand the light distribution. At the end he defined an action plan to improve the light range and homogeneity.