DePalma was immediately successful in car racing. In 1911, DePalma won the first Milwaukee Mile Championship Car race. However, he is still remembered for the dramatic manner in which he lost the 1912 Indianapolis 500. After leading the race for 196 of the 200 laps, his Mercedes cracked a piston and with only 2 laps remaining; he and his mechanic had to push the car across the finish line to take eleventh place. At that time, only cars completing the full 200 laps received any prize money. This Mercedes remains on display at the Indianapolis Motor Speedway Hall of Fame Museum.