Two C-4R roadsters were built, as well as a single coupe with truncated bodywork designed in collaboration with German aerodynamicist Wunibald Kamm that was designated the C-4RK.[2] During practice at the 1952 24 Hours of Le Mans the new transmissions caused problems, and were replaced with 3-speeds. In the end the C-4R of Briggs Cunningham and Bill Spear finished fourth overall.[32] At the 1953 24 Hours of Le Mans a C-4R roadster finished seventh, and the C-4RK coupe tenth. The C-4Rs returned to La Sarthe in 1954 to take third and fifth. A C-4R won the 1953 12 Hours of Sebring. In 1954, a C-4R driven by Briggs Cunningham and Sherwood Johnston finished sixth in the 12 Hours of Reims.
