Since 1953 Vittorio Bellentani had been working on a 1.5 liter engine for a new sports car, but the mechanical configuration, 4 cylinders, double overhead camshaft, two Weber double barrel carburetors and twin ignition were first used by Liborio Guidotti for his racing boat Maria Luisa IV which broke a speed record.

On the car side, the chassis was modified with the adoption of a "De Dion" bridge and the bodywork was entrusted to Celestino Fiandri, on the basis of the 300S.

From her first races, she made a name for herself, in particular by beating 13 Porsches and 4 BMWs in the 500 km of the Nurburgring, driven by Jean Behra, in 1955. She then had a brilliant career and won a dozen victories in total.