In 1968, Ahrens Jr. joined the Porsche factory sports car team and shared victory with Jo Siffert in the 1969 Austrian 1000 km event. He co-drove the pole-setting Porsche 917 "long tail" at the 1969 24 Hours of Le Mans and the 1970 24 Hours of Le Mans, but neither car finished. In 1970, he partnered with Vic Elford to win the 1000km Nürburgring in a Porsche 908.