1915 Grand Prix season

The 1915 Grand Prix season saw Grand Prix motor racing continue in the United States. Racing was suspended in Europe due to the outbreak of World War I. The American Grand Prize was held in San Francisco for the first time, in conjunction with the Panama–Pacific International Exposition. Several of the latest European cars had been imported to the USA before the war started. Briton Dario Resta had a Peugeot and Ralph DePalma raced one of the Mercedes GPs. While Resta won both races at San Francisco and DePalma won the Indianapolis 500, just ahead of Resta it was Earl Cooper, running a Stutz, whose consistency gave him the unofficial AAA national championship.

1915 Grand Prix season

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1916

Major races

Sources:^[1][2][3][4]

Date	Name	Circuit	Race Regulations	Race Distance	Winner’s Time	Winning driver	Winning constructor	Report
27 Feb	VI American Grand Prize	San Francisco	AAA	400 miles	7h 08m	Dario Resta	Peugeot EX-3	Report
6 Mar	X Vanderbilt Cup		AAA	300 miles	4h 28m	Dario Resta	Peugeot EX-3	Report
31 May	V Indianapolis 500	Indianapolis	Indianapolis	500 miles	5h 34m	Ralph DePalma	Mercedes 18/100	Report

Regulations and technical

This year the Grand Prize and Vanderbilt Cup’s engine limits were both matched to those of the Indianapolis regulations - down to 450 cu in. Then Indianapolis lowered their engine limit down to 300 cu in (4.92 litres) along with the additional restriction that only three cars from each manufacturer could be entered.^[5]

The war in Europe meant some of the most technically advanced cars were sold and crossed the Atlantic, adding vitality and innovation to the American manufacturers just as they were making their own technical strides.^[6]