A designer with the Fiat racing department in the late 1920s Massimino moved to Alfa Romeo after the company withdrew from competition. Massimino worked with Alfa Romeo until the split with Enzo Ferrari after which he joined Ferrari's nascent operation but in 1944 he was lured away from Modena to become the technical director of Maserati, which had by then been taken over by the Orsi Family. He revamped the Maserati 4CL which had been designed in 1939 by Ernesto Maserati, and the 4CLT was highly successful in the immediate post-war period. He then designed a new A6GCS sportscar and in 1952 this design was reworked into a Formula 2 car which became known as the A6 GCM and later as the A6SSG. In 1953 Juan-Manuel Fangio won the World Championship in one of the cars. Maserati then hired Gioacchino Colombo and Massimino worked with him on the development of the Maserati 250F, one of the greatest F1 cars of all time.