frustrated with the poor build quality of its racing cars. At the Coppa Acerbo, Alfa Romeo's new 12C-37 car proved to be slow and unreliable. Frustrated, Nuvolari handed his car over to Giuseppe Farina mid-race. Not wanting to leave Alfa Romeo, he drove an Auto Union in the Swiss Grand Prix as a one-off. After the Italian Grand Prix, Alfa Romeo withdrew from racing for the remainder of the season and dismissed Vittorio Jano, its chief designer. 1938–1939: Auto Union 1938 Although Nuvolari started 1938 as an Alfa Romeo driver, a split fuel tank in the first race of the season at Pau was enough for him to walk out on the team, critical of the poor workmanship that was exhibited. He announced his retirement from Grand Prix racing and took a holiday in America. At the same time, Auto Union was having to rely on inexperienced drivers. Following the Tripoli Grand Prix they contacted Nuvolari who, having been refreshed from his break, agreed to drive for the highly successful German team, who were running radical mid-engined cars. Nuvolari found further success with Auto Union; now driving a faster and more reliable car that enabled him to compete for victories and the European Championship, Nuvolari won his home Grand Prix at Monza and won the Donington Grand Prix in England. 1939 In 1939 he won Belgrade Grand Prix which was held on 3 September 1939, the last one before outbreak of World War II. Post-war racing In 1946 Nuvolari took part in thirteen races, winning the Grand Prix of Albi in a Maserati 4CL, finishing 4th in the Grand Prix of Nations and 13th in the Coppa Brezzi, and retiring from the others. It was noted that when he raced at Milan in September, he steered with mostly one hand; the other held a bloodstained handkerchief over his mouth. Through 1947 and 1948 he raced eleven times, winning twice. He finished 2nd, 3rd, 4th, and 7th, and retired from the remaining five races. His Maserati did not qualify for the 1949 Marseilles Grand Prix. Battered by health problems as well as the loss of his two sons, Nuvolari was nevertheless persuaded by Enzo Ferrari to race in the 1948 edition of the Mille Miglia. Paired with mechanic Sergio Scapinelli, Nuvolari took the lead in the early stages of the race. He was eventually forced to retire the car in Reggio