Renault 4CV Rosier Special

The Renault 4CV Rosier Special was a limited-production, competition-oriented berlinette constructed between 1951 and 1953 on the basis of the standard Renault 4CV. The project was initiated by French racing driver and Renault distributor Louis Rosier, and executed in collaboration with Italian coachbuilder Rocco Motto. The vehicle was intended for light competition use, with mechanical modifications and aerodynamic bodywork differentiating it from the production 4CV. The chassis employed was that of the Renault 4CV, featuring a rear-mounted, water-cooled inline four-cylinder engine with overhead valves. In standard configuration, displacement was 747 cc, producing approximately 21 horsepower. For the Rosier Special, the engine was enlarged to an estimated 904 cc and fitted with a high-compression head and twin carburetors. Output was increased to approximately 55–60 horsepower. Power was transmitted to the rear wheels via a three-speed manual gearbox. Suspension consisted of independent front and rear arrangements with coil springs and swing axles. Braking was by hydraulic drums on all four wheels. The coachwork was fabricated by Rocco Motto in aluminum over a tubular steel frame. The body featured a streamlined berlinette profile with a fastback roofline, low frontal area, and integrated fenders. The overall design prioritized aerodynamic efficiency and reduced weight, with total mass estimated at approximately 465 kilograms. The cabin accommodated two occupants and was fitted with minimal instrumentation and trim, in accordance with competition requirements. Production was limited. Sources suggest that no more than three examples were constructed, with one confirmed vehicle, chassis number 1562329, entered in the 24 Hours of Le Mans in 1953. Driven by Jean-Louis Rosier and Robert Schollmann, the car competed in the sub-1100 cc category. Additional appearances in national rallies, including the Monte Carlo Rally, are attributed to the same vehicle. No comprehensive ownership history has been published. The known example passed through private collections and is believed to survive, though its current condition and location are not publicly documented. The Renault 4CV Rosier Special stands as a rare example of cross-national postwar collaboration, combining a mass-produced French platform with bespoke Italian coachwork for competitive use. It occupies a peripheral but noteworthy position in Renault’s early motorsport history.