Before the Porsche job, Hatz was the head of engine and powertrain development for the Volkswagen Group. It has been alleged that he is at the center of the investigation into the company cheating on emissions testing, but so far there has been no direct link made to him, according to Porsche's announcement today. Hatz has worked at a variety of European automakers, including Audi, BMW, Opel, and Fiat. He is considered the father of the BMW S14 engine, which powered the E30 M3, and also developed the Porsche 911 Carrera RS 3.8. He was also very involved in Porsche's motorsports efforts, including the recent return to the prototype class and a short-lived F1 V12 engine project.
Ulrich Hackenberg, most recently VW's lead engineer and a board member at Audi, was also suspended at the same time as Hatz and resigned shortly thereafter. It's not clear why Hatz waited so long to do the same, but Porsche claims his resignation was voluntary.
Michael Steiner has been named Hatz's replacement as head of Porsche R&D. Steiner has been with Porsche since 2002 and seems like a forward-thinking sort, having headed the innovation and concepts division, lead Panamera development, and, most recently, been in charge of complete vehicle engineering. Prior to his time at Porsche, Steiner held positions at Daimler. The change in leadership is effective immediately.