An expatriate from Chili, Zanelli was a humorous, carefree person with a chubby face who lived in France Italy and Spain in the 1920s and 1930s. He was a typical Bugatti independent driver, racing in Grand Prix and hillclimbs starting with a Fiat in 1926. It is not clear what his occupation was but it seems that he was a member of the Chilean diplomatic service and was at one time the Chilean consul in Nice.
In 1929 he won the Bugatti GP on June 2nd, the annual race organized by Ettore for Bugatti owners at Le Mans for which a new Grand Prix Bugatti was the prize. He also cane second in the Marne GP. He led the Grand Prix de l'ACF but retired.
In 1930 he won the Bugatti GP again, came third in the French Grand Prix at Pau and second in Alexandia. In hillclimbing he won at Gometz-Le Chatel.
In 1931 Zanelli raced a Nacional Pescara. This was powered by a supercharged eight-cylinder twin overhead cam 2.8 litre engine developing 260 b.h.p.. The car was built by the Spanish Fabrica Nacional de Automoviles, an enterprise backed by the Spanish royal family.
Zanelli won the European Mountain Championship in this car, taking victory along the way at Kesselberg ahead of Caracciola in a time of 4 minutes 4/10th second. At Shelsley Walsh that year he made the climb in 44.4 seconds.
It is worth noting ttat the Spanish Nacional Pescara team of Zanelli and Tort had a considerable advantage over the competition. They had taken the trouble of registering, so even though the fastest times often went to the likes of Caracciola, Stuck and Varzi, the Nacional-Pescara drivers took most of the points. Zanelli took only one outright win, yet his third, fourth and sixth place finishes in other rounds all yeilded maximum points.
From 1933 to 1935 he raced his private Alfa Romeo Monza (2111042) winning the 1933 Penya Rhin. He also finished 8th in the Tunis GP and 6th at the Brooklands 500.
At the same time he continued to race the Nacional Pescara, now rebodied as a Monoposto, in hill climbs winning at Val de Guech in 1935.
In 1936 he raced a V8-Ri Scuderia Torino and a Maserati 8CM for Scuderia Villapadierna, finishing third at La Turbie hillclimb in the ageing Nacional Pescara.
Zanelli quit racing at the end of 1936.
He died in 1942 in a camp where he had been interred for his participation in the Resistance movement.