In spite of the war the design of the 4CV had been under development since 1941. Ferdinand Porsche, designer of the Volkswagen, even provided technical advice after the war when he was incarcerated in a French prison on trumped up war crimes charges. Louis Renault had also been imprisoned as a Nazi collaborator during the war, and had died in prison.
4CV prototype testing began in 1946 and the new post-war Renault 4CV was introduced at the 1947 Paris Auto Show. It began arriving on our shores in 1949, and what greeted North Americans was a tiny four-door sedan (a convertible was also offered) with its front doors hinged at the rear, "suicide" style. It was powered by an overhead valve, four-cylinder, inline engine.
Because Louis Renault had been influenced by Porsche's rear-engine Volkswagen design of the 1930s, Renault had the 4CV's engine mounted longitudinally behind the rear axle. It initially had 760 cc, but was decreased a few years later to 747, which brought it within the 750 cc racing class.