The 1931 Grand Prix season was a watershed year, with the advent of the AIACR European Championship. After several years of Grand Prix racing in the doldrums with little technical development, 1931 saw new models come from all three main manufacturers: Bugatti, Maserati and Alfa Romeo.
The AIACR regulations were to Formula Libre (open formula) rules for the cars, but the race-format chosen was to run the Grands Prix over a marathon ten hours each with two drivers per car. The pair had to be the same for all three races otherwise only the lead driver would score points. The championship was won by Ferdinando Minoia, driving for the Alfa Corse works team. He was tied on points with his team-mate Giuseppe Campari after the three races. Despite not having won any of the races, his consistency gave him the tiebreaker by covering a greater distance across the combined 30 hours of racing. However, the endurance format of the series was exhausting and unpopular with the drivers, and became processional and boring for the spectators and would not be repeated.
In the other major races of the season, the new Bugatti Type 51 won its first event, at Tunis, and dominated the French circuits in the early half of the season. The Italian Championship regularly drew the best drivers and gave close racing between Alfa Romeo, Bugatti and Maserati. At the end of the season, the championship was awarded to Alfa Romeo driver Campari, on a tie-breaker countback. With both major titles in their cabinet, Alfa Romeo finished the season strongly.