In 1995, he won the title "Best Rookie " at the Monaco Formula 3 Grand Prix. A year later, he finished second at the International German Formula 3 Championship. In 1997 he succeeded the Porsche Carrera Cup third place overall and became the "Best Rookie of All Time". For BAM Racing was Klaus Graf 2004, two races in the NASCAR Nextel Cup, now the Sprint Cup contest, but could not qualify for the race at Watkins Glen because of rain and the regulations of NASCAR. For the race at Infineon Raceway at Sears Point, Klaus Graf qualified as the 38th of 43 riders. He completed the race from the 17th, before long-established NASCAR drivers like Dale Jarrett and Matt Kenseth. In 2005 he started for Rocket Sports Racing in the Trans-Am and became the first German winner of this race series. In 2006 he started with Mike Rockenfeller Porsche 996 GT3 RSR for Alex Job Racing in the ALMS. In 2007, he appeared with his new team Cytosport at some selected rounds of the ALMS.
In the NASCAR Nextel Cup, he replaced in the 2007 season for the two road course races at Infineon Raceway and Watkins Glen International Mike Bliss for BAM Racing. However, he could not qualify for both races. On the Infineon Raceway the car itself was too slow in Watkins Glen failed to qualify at the termination of the session due to rain, so that the preparation according to owner points was made and Count outside the top -43 did not get a starting place due to the placement of the car.
In addition to his racing career, he is a freelance racing coach and instructor and test driver for various companies. For the pay-TV channel Premiere, he was a co-commentator and expert on NASCAR races, and occasionally other racing events, such as the recent 24 Hours of Le Mans, works.
On March 20, 2010 Klaus Graf won with his team-mate Sascha Maassen ( Aachen ) and Greg Pickett (USA ) on a Porsche RS Spyder, the famous 12 - hour race at Sebring in the sports car prototype LMP2 class in the American Le Mans Series. This Porsche sports cars they won also the environmental Michelin Green X Challenge, because this vehicle had the best overall efficiency in the ratio of lap times and fuel consumption.
Klaus Graf is married and has two children.