Alfa Romeo 6C 2300 B Cabriolet Aerodinamico Castagna

The Alfa Romeo 6C 2300 B Cabriolet Aerodinamico by Carrozzeria Castagna was a custom-bodied, one-off vehicle constructed in 1937 on the 6C 2300 B short-wheelbase chassis. It was publicly exhibited that year at the Salone dell’Automobile di Milano. The car’s aerodynamic styling and mechanical base placed it within a select group of experimental bodies presented at the show, reflecting an increasing interest in streamlined forms and transatlantic design influences. The vehicle was equipped with the standard mechanical specification of the 6C 2300 B series. The engine was a 2,309 cc inline-six with dual overhead camshafts and hemispherical combustion chambers, producing approximately 76 CV at 4,400 rpm. A four-speed manual gearbox transmitted power to the rear axle. The chassis featured independent front suspension with a double wishbone and coil spring layout, and independent rear suspension by swing axles with longitudinal torsion bars. Four-wheel hydraulic drum brakes were standard. The bodywork created by Castagna was an early exercise in aerodynamic experimentation. The design incorporated a long, fastback profile with covered rear wheels, concealed door hinges, integrated headlamp pods, and a distinctive vertical grille reminiscent of American models such as the Cord 812. The use of flush surfaces and curved lines marked a departure from the more upright touring bodies traditionally associated with Italian coachbuilding in the early 1930s. This specific cabriolet was displayed on the Castagna stand at the 1937 Milan Motor Show. A second example, similar in form but differing in detail, was simultaneously exhibited on the Alfa Romeo factory stand. That second vehicle was constructed on the same chassis type and intended to demonstrate parallel approaches to streamlined luxury. The presence of two experimental aerodynamica bodies at a single event underscored the growing influence of aerodynamic theory on both manufacturer and coachbuilder practice during the late interwar period. No production run followed, and only the two documented examples are known to have been constructed. Chassis numbers are unrecorded in surviving archives. These vehicles represent transitional works at the threshold between traditional coachbuilding and the emerging industrial aesthetics of the 1940s.