Lietz won the 2012 24 Hours of Daytona GT division driving a Magnus Racing Porsche 911 GT3 Cup with co-drivers Andy Lally, Rene Rast and team owner John Potter. He will compete in the FIA World Endurance Championship with Team Felbermayr-Proton. In 2015 he was crowned World Endurance Champion for GT drivers. Winning the title in a factory Manthey Porsche.
