Theys is an endurance driving legend, a 2002 Grand Am national champion and a former Indy car star. He won the Daytona 24 hour race and Sebring 12 hour race in 1998. He won Daytona again in 2002.
Didier Theys was born in Nivelles, Belgium, now based in Scottsdale, Arizona. Theys started racing go-karts in Belgium in 1974, winning the Belgium Karting Championship in 1977. He quickly advanced through the ranks of Formula Ford, Formula 3 and Formula 2 before being invited to the United States to compete in the SCCA's Pro SuperVee Series, winning the championship in his second year of competition.
Theys caught the eye of Steve Horne, team manager for TrueSports Racing, who recruited him to drive their Indy Lights car. He won the American Racing Series (Indy Lights) championship. That year he also raced in CART Indy Cars series and won the Spa Touring Car 24 Hour race.
After winning the championship, he graduated full time into the CART series, signing for Dick Simon's team. He raced in the 1987-1993 seasons with 47 career starts, including the 1989, 1990 and 1993 Indianapolis 500. He finished in the top ten 10 times and his best career finish was in 3rd position in Miami.
While racing with CART, Theys also dabbled in with sportscar racing, paving the way for steady employment later in his career.
Theys has raced and won races with IMSA and the Grand-Am Rolex Series. He had one of his best years in 1998, when he won his first Rolex 24 at Daytona, the 12 Hours of Sebring and the Six Hours at the Glen. Also, he captured an FIA Sports Car Championship at Paul Ricard, France. He won the Daytona Prototype championship in Grand-Am in 2002 with Fredy Leinhard, Jr.
Theys earned the 2002 driver championship in the premier Sports Racing Prototype class in Grand Am that year, while his team, Doran-Lista Racing, finished second in the team standings for the third consecutive year. Theys led the Grand Am SRP point standings all year in 2002, with victories at the Rolex 24 Hours of Daytona, Homestead, Fontana andMont-Tremblant. He earned seven poles in the 10-race series and won the driver's championship in the premier Sports Racing Prototype class. Although it was his first Grand Am championship, he finished in the top three in 2000, 2001 and 2002 in Grand Am SRP points.
Theys only ran the first three of nine races in the ALMS in 2003 in the Doran-Lista Dallara and finished 14th in the overall 2003 LMP900 point standings. Theys also competed in six of the 12 Grand Am events in 2003 in the brand-new Daytona Prototype class while helping to develop the brand-new DORAN JE4 chassis. He ran two of those races with Bell Motorsports and four with Doran-Lista Racing to finish eighth in Daytona Prototype points.
In 2004 he finished seventh in Daytona Prototype points for the year and in 2005 he only drove in a few selected races with Doran Racing, finishing fifth in the Rolex 24 Hours at Daytona with teammates Fabrizio Gollin and Matteo Bobbi.