Kling was instrumental in developing Mercedes' return to international competition in the early 1950s, and his win in the 1952 Carrera Panamericana road race, driving the then-experimental Mercedes-Benz 300SL was a defining point in assuring the Daimler-Benz management that motorsport had a place in Mercedes' future. Called up to the revived Mercedes Grand Prix squad in 1954 he finished less than one second behind the legendary Juan Manuel Fangio on his Formula One debut, taking second place in the 1954 French Grand Prix at the fast Reims-Gueux circuit. This promising start was not to last, and with the arrival of Stirling Moss at Mercedes in 1955 Kling was effectively demoted to third driver. However, away from the World Championship, Kling took an impressive victory in the Berlin Grand Prix (at AVUS, another high-speed circuit). He left the Formula One team at the end of the season, to succeed Alfred Neubauer as head of Mercedes motorsport. He was in this post during their successful rallying campaigns of the 1960s, occasionally taking the wheel himself. On one such occasion he drove a Mercedes-Benz 220SE to victory in the mighty 1961 Algiers-Cape Town trans-African rally.