Alfa Romeo 6C 1750 GT Drophead Coupé Castagna

The Alfa Romeo 6C 1750 GT Drophead Coupé by Castagna, chassis number 10914408, was constructed in 1931 on the fifth series of the 6C 1750 chassis. This series represented the evolution of the 6C 1750 Gran Turismo configuration, which was produced in limited numbers from 1930 to 1932. Carrozzeria Castagna of Milan was commissioned to design and fabricate the open two-door bodywork for this example, resulting in a rare drophead coupé configuration of which only two examples are believed to have been executed by the coachbuilder. The vehicle is powered by a 1,752 cc inline-six-cylinder engine equipped with double overhead camshafts and a Roots-type supercharger, in keeping with Alfa Romeo’s period practice for performance-oriented variants. Power output in this specification is estimated at approximately 80 horsepower. The transmission is a four-speed manual unit delivering power to the rear axle. Suspension consists of semi-elliptical leaf springs both front and rear, with braking handled by mechanical drum brakes on all four wheels. The chassis retains the ladder-type construction consistent with contemporary Alfa Romeo engineering principles. The Castagna coachwork is rendered in a restrained yet elegant style. The drophead coupé features long front wings, a low folding windshield, and a rear section that accommodates the convertible top within a tapered tail. Exterior embellishment is limited, with brightwork confined to the radiator surround and minor trim elements. The body is constructed in aluminium and steel over a timber frame. The interior is finished in leather, with a wood-veneered dashboard and period-correct instrumentation. Chassis number 10914408 is believed to retain its original engine and bodywork. Production records indicate that 652 units of the 6C 1750 GT were manufactured, of which only a small proportion were bodied by Castagna, and only a limited number in open configurations. The vehicle has been associated with prominent early owners, with reports linking its initial delivery to Tazio Nuvolari, although documentation remains inconclusive.