His greatest successes were in sportscar racing, winning the Targa Florio in 1952, but his career was cut short when he fatally collided with a lamp post whilst leading the 1953 Carrera Panamericana.

He entered his own Maserati 4CLT in several Grands Prix, under the Scuderia Milano banner, and drove a works Alfa Romeo SpA in 1951, as their number three driver.

A move to sports cars followed, but he returned to Formula One at the end of 1952 and had a good season in the Officine Alfieri Maserati in 1953, with a visit to the podium, when he again shared a third-place finish in the Grote Prijs van Nederland.

He followed this with a sixth place in the Preis von Bremgarten and an eighth in the les 24 Heures du Mans, and finally a great win in the Targa Florio.

He continued with the Scuderia Lancia outfit for 1953; claiming third in the Mille Miglia, second in the Gran Premio di Monza, victory in the Grande Premio do Jubileu at the Circuito de Monsanto and he became part of the squadron deployed to the Carrera Panamericana: his teammates for the race were Juan Manuel Fangio, Piero Taruffi, Giovanni Bracco and Eugenio Castellotti.

[3][4][5][10] The Carrera Panamericana, a notoriously dangerous and difficult public road rally in Mexico that took place over 6 days from one end of the North American country to the other, covering a distance of 2,000 miles (3,200 km).

It was the last round of the 1953 World Sportscar Championship, and the race started on 19 November 1953, from Tuxtla Gutiérrez; Bonetto won the first stage, in front of his teammates Taruffi, Fangio and Castellotti.

Prior to the event, Bonetto with Taruffi and other Italian drivers reportedly marked dangerous corners along the route with blue signs.

Fangio, Taruffi and Castellotti led to the finish giving Lancia first three places, but it was a success that was not rejoiced, as besides Bonetto the race also claimed the lives of fellow Italian drivers, Antonio Stagnoli and Giuseppe Scotuzzi, as well as six spectators.