Stommelen was born in Siegen, Prussia. He came to prominence in endurance racing before establishing himself in Formula One. In 1967 he won the Targa Florio with Porsche, one of the most demanding road races in the world. The following year he took his first 24 Hours of Daytona victory, also with Porsche. His technical mastery of the Nürburgring Nordschleife in particular made him a consistent frontrunner in German and European sportscar events.
At the 1969 24 Hours of Le Mans, Stommelen qualified the Porsche 917 on pole position. During practice he became the first driver to exceed 350 km/h (217 mph) on the Mulsanne Straight, a landmark moment in the history of the circuit. He had finished third at Le Mans the previous year in a Porsche 908.
Stommelen made his Formula One debut with Brabham in 1970, his entry supported by the German magazine Auto, Motor und Sport. He raced concurrently in both Formula One and sportscars throughout the first half of the decade. Across 63 World Championship Grands Prix, he achieved one podium and accumulated 14 championship points.
The defining and most tragic moment of his Formula One career came at the 1975 Spanish Grand Prix at Montjuich Park in Barcelona. The rear wing of his Hill GH1 failed at speed, sending his car into the crowd. Five spectators were killed and Stommelen was seriously injured. The accident ended the Spanish Grand Prix's association with the Montjuich Park circuit permanently.
After recovering from his injuries, Stommelen returned to sportscar racing with renewed success. He drove for Alfa Romeo and recorded further victories in endurance competition. In 1976 he drove the maiden race of the Porsche 936 at the 300 km Nürburgring event. In a rain-soaked race, he wrested the lead from the factory Renault-Alpine entries and, after the throttle cable stuck open, completed the race by switching the ignition off at corners to brake and on again to accelerate — finishing second. The episode gave rise to the enduring saying among Nürburgring regulars: "On the Nordschleife, you can never brake later than Rolf Stommelen."
In 1977 he won the German GT Championship Deutsche Rennsport Meisterschaft for the Gelo Racing Team in a Porsche 935. The following year, 1978, Porsche assigned him the 935 "Moby Dick" — a 3.2-litre turbocharged machine producing approximately 845 horsepower. At Le Mans that year, Stommelen was recorded at 235 mph (365 km/h) on the Mulsanne Straight, faster than the prototype Porsche 936 and the Le Mans-winning Renault Alpine A442B. He also took his second Daytona 24 Hours victory in 1978.
In 1979, Stommelen came close to winning Le Mans outright, sharing a Porsche 935 with Dick Barbour and actor Paul Newman. A 23-minute pit stop caused by a stuck wheel nut denied the team the lead they had earned through Stommelen's consistently faster lap times compared to his co-drivers. He won the Daytona 24 Hours again in 1980 and 1982, giving him four victories at that event in total.
On 24 April 1983, during a 6-hour IMSA GT Championship race at Riverside International Raceway in California, Stommelen had just taken over a John Fitzpatrick-entered Porsche 935 from co-driver Derek Bell. Running in second place, the rear wing broke due to mechanical failure at approximately 190 mph (306 km/h). The car became uncontrollable, hit a concrete wall, somersaulted, and caught fire. Stommelen died of blunt force trauma and crush injuries to the chest and head. He was 39 years old.
Stommelen's career embodied the generation of European drivers who moved fluidly between Formula One and endurance racing during the 1970s. His four Daytona victories, the Targa Florio win, his repeated dominance at the Nürburgring, and the sheer physical courage he demonstrated driving high-powered machinery in all conditions mark him as one of the most capable and versatile German racing drivers of his era. The 1975 Montjuich Park accident, while not of his making, changed the safety expectations for street circuits across motorsport. His death in 1983, like that of several contemporaries, came from the same recurring failure mode — a structural collapse at high speed — that the sport was only beginning to address seriously.