Martin Winterkorn is the former chairman of Volkswagen AG and Audi AG. He studied metallurgy and received his PhD from the University of Stuttgart. Winterkorn began his career at Robert Bosch GmbH in 1977 and held several management roles at Bosch and Volkswagen subsidiaries. He became CEO of Audi AG in 2002 and CEO of Volkswagen AG in 2007, leading initiatives to make Volkswagen the world's largest automaker by 2018. Winterkorn resigned as chairman of Volkswagen Group in 2015 due to the company's diesel emissions scandal.