For seven seasons Wirth competed in the ADAC GT Masters series where he tallied a total of 9 victories.

After sitting out 2007, Wirth competed in 3 Atlantic races in 2008 and also drove for Panoz Team PTG at the 2008 Petit Le Mans.

Wirth returned to Europe in 2009, racing for Alpina in the ADAC GT Masters, winning once with co-driver Jens Klingmann.

Wirth joined Heico Motorsport in 2011, finishing 9th in the championship and winning one race with co-driver Christiaan Frankenhout.

In 2016, Wirth finished 3rd in the European Le Mans Series LMP2 championship with Stefano Coletti, driving the SMP Racing BR01 prototype.