Complex sentence: He is also a member of the executive committee (since 1991), executive committee speaker (since 1992), a member of the supervisory board of Volkswagen (since January 28,2006) and the president of Porsche.
Split into simpler sentences: He is also a member of the executive committee (since 1991), executive committee speaker (since 1992). In addition he is a member of the supervisory board of Volkswagen (since January 28,2006) and the president of Porsche.