In 1989 Giroix joined the DTM circuit full-time driving a BMW M3 for Schnitzer Motorsport, finishing 3rd in points with 10 podium finishes in 21 starts. He also drove in the 24 Hours of Nürburgring and with teammates Emanuele Pirro and Roberto Ravaglia won the race in their Team Bigazzi BMW M3. In 1990 he dropped to 9th in points for the same team but won the Spa 24 Hours with teammates Johnny Cecotto and Markus Oestreich.