350S

The 350S was equipped with an even bigger 6-cylinder engine of 3.5 litres. The engine was a prototype of the 3500 GT production car and was not directly related to the 300S's power unit which had reached its limits of development. Three cars were built with a 5-speed transaxle gearbox from the 450S. Two cars were sold to the US where one was later raced with a Corvette V8 engine.

The third 350S was fitted with the Maserati V12 cylinder from the 250F T2 Grand Prix car, enlarged to 3.5 litres and producing 335 bhp. It was prepared for the 1957 Mille Miglia where it was driven by German ace, Hans Hermann, who unfortunately retired. It was also entered in the 500 Miles of Monza against the American Indy roadsters. It was later returned into its original 6-cylinder configuration and sold to Brazil.