The 1952 roadster-bodied C-4R and C-4RK coupe were smaller and lighter than the earlier cars and, thanks to more engine development, were now putting out 325 horsepower. Once again, a three-car, six-driver team took up the challenge at Le Mans, and once again, two cars retired, but Briggs drove the race of his life, staying in the cockpit for almost twenty hours before handing the car over to Bill Spears. They finished an incredible fourth place.

Team Cunningham scored more victories back home in the U.S., and in 1953 more developed versions of the C-4R and C-4RK finished seventh and tenth respectively at Le Mans, while the new C-5R, long considered the best of the racing Cunninghams, finished third overall, a mere forty-two miles behind the second of two disc-brake-equipped Jaguar C-Types. Reflecting on the event years later, Briggs commented, "Three cars, third, seventh and tenth, in the top ten at Le Mans. I guess that's not too bad."

Serving yet another tour of duty in 1954, the two C-4Rs finished at Le Mans in third (Spears /Johnston) and fifth (Cunningham/Benett), while a newly-acquired Ferrari 375MM (Fitch/Walters) retired with broken valve train.