The 1930 Grand Prix season continued the malaise that had taken over the sport. Although there was little technical advance more privateer teams were forming, getting some factory support. The AIACR continued to mandate its fuel-regulated Formula Libre (open formula) rules. Across the Atlantic, the AAA abandoned the AIACR regulations. Their new regulations were derisively called the “Junk Formula” by purists, opening up to their own version of Formula Libre: with modified stock-standard cars of up to 366 cu in (6-litres) with two seats.
In the dozen major races of the season, the honours were evenly shared by the three major manufacturers. Bugatti won the two national Grands Prix of France and Belgium, as well as at Monaco and Reims. In the Mediterranean theatre, Alfa Romeo had early success at Alessandria and the Targa Florio. Maserati finally claimed victory in their first major races, and had four wins in Italy and the San Sebastián Grand Prix in Spain. Achille Varzi was the pre-eminent driver of the season with the two race-wins for Alfa Romeo and three for Maserati, on his way to winning the Italian Drivers’ Championship.
The Indianapolis 500 produced one of the most dominant driving displays in the race's history with Billy Arnold and his modified 2.5-litre Miller. Arnold claimed pole position then led for all but two of the 200 laps, to win with a four-lap margin. With two further victories, he then went on to claim the 1930 AAA champion.