He competed in German Formula Three for his father's team for the next three years, before moving to the Deutsche Tourenwagen Masters for 2002.

On 5 June 2011 Mücke was involved in incident with Richard Westbrook during FIA GT1 World Championship race at Silverstone.

The first took out David Brabham at 'The Cutting', the second on the last corner of the last lap forced Matt Bell wide, depriving the latter of a podium place.

In the 80th, edition of the 24 Hours of Le Mans in 2012, Mücke and the Aston Martin Racing got the third place in the GTE-Pro class along with his co-drivers the Mexican Adrián Fernández and the British Darren Turner, their Aston Martin Vantage 4.5 L-V8 covered a total of 332 laps (2,811.65 miles), in the Circuit de la Sarthe without failure or serious mechanical problems.

[4][5] In 2016, Stefan joined Ford Chip Ganassi Racing UK's two-car FIA World Endurance Championship LMGTE Pro effort after eight seasons with Aston Martin.