The 1915 Indianapolis 500 was won by Ralph DePalma in a Mercedes. he set a new speed record with just under 90 mph. The race was scheduled for Saturday, May 29, but due to heavy rain, the start had to be postponed to Monday, May 31. This year, it looked like the overhead valve engines were to make their breakthrough and the Stutz cars made very promising appearances. As the First World War raged for almost a year in Europe, hardly any European magazine reported on American races.