Didier moved to auto racing from a successful 10 year World Championship motorcycle career including five Grand Prix wins. He drove for the BMW factory team in the inaugural International Sports Racing Series in 1998. Winning the 1998 24 Hours of Spa-Francorchamps along with the Belgian ProCar Class 1 Championship. Didier capped a great season with an overall victory in a factory BMW at the Visa Sports Car Championship at Laguna Seca, the final race of the Sports Car Series. In 1999 he was on the podium at the world-famous 24 Hours of Daytona when he finished second driving for the Olive Garden racing team. Didier had one podium finish in the 2000 ALMS season, bringing the Team Rafanelli V-10 home third at Charlotte. Driving the Reynard O1Q in the LMP-675 class of the 2001 ALMS he drove to victory six times. This included one ELMS win at Jarama, Spain and subsequent ALMS victories at Sears Point, Portland, Mosport, Mid-Ohio and Laguna Seca. Didiers third place finish at the Petit Le Mans, despite lengthy technical problems was a key to the Dick Barbour Racing team's claim to both the ALMS and ELMS class championships. To reward his overall outstanding driving performance, Didier was awarded the 2001 ALMS/LMP-675 class Drivers Championship.