Born in 1908 in Biella, Trossi had a twenty year career in motorsports, racing predominantly in Alfa Romeos and Maseratis, and with a brief tenure as President of Scuderia Ferrari. He passed away while still young, defeated by cancer in May 1949.
Trossi began racing at a very young age, and scored his first major victory in 1931, with a class win in the Biella-Oropa race. The following year, he finished the Mille Miglia in second overall place at the helm of an Alfa Romeo 2300 as a two-driver team with Brivio and, as reigning champion from the previous year, won the Coppa Gallenga and the Biella-Oropa. In 1933, in an Alfa Romeo of the Scuderia Ferrari, he racked up five consecutive wins (Florence Circuit, Pontedecimo-Giovi, the Gaisberg Hill Climb, Targa Abruzzo and the Stelvio Hill Climb), and took second place at the Alessandria Circuit and third at the Monaco Grand Prix.
In 1934 he won at Biella, Vichy and Montreaux, took second place at Alessandria and Kesselberg, and came third at the Italian Grand Prix. He moved over to Maserati in 1935, and the following year, he drove cars with the Trident badge to victory in the 1500 class of the Italian race car championship. 1937 saw him swapping between Maseratis and Alfa Romeos. Driving Maseratis, he won at Naples and Lucca, came second at Florence and finished sixth at Crystal Palace, while at the wheel of Alfas, he scored respectable results at the Italian Grand Prix and at the Valentino Circuit in Turin. In 1940, he defended the colours of the Alfa Corse team together with Farina and Pintacuda.
After the war, he went back to Alfa Romeo, forming a tightly knit team with Varzi and Wimille. During this period he brought home a magnificent win at the 1947 Italian GP disputed at the Fiera Campionaria Circuit in Milan, and – in his last victory – triumphed at the 1948 Swiss Grand Prix at Bremgarten. He dedicated this win to his team mate Varzi, who had been killed a few hours earlier in practice.