In 2005 Dumbreck returned to Japanese Super GT (JGTC/Super GT) in the midst of the season, driving a Toyota which became Lexus from 2006 to 2008.
In 2006, he returned to Le Mans and drove the No. 85 Spyker Spyder for Spyker Squadron in the GT2 class, but that car retired with only 40 laps completed resulting in 47th finish overall.