Jim Malloy began racing modifieds at Denver’s Lakeside Speedway in 1952. He was the track champion from 1959 through 1961. He then joined the Canadian-American Modified Series in 1962 and won their championship from 1963 through 1965. From there, he started racing United States Auto Club Champ Cars in 1967 and was the fastest rookie to qualify for the 1958 Indianapolis 500. Malloy raced in the Indianapolis 500 from 1968 through 1971, scoring a fourth place finish in the 1971 race. This was the highest finish for any Colorado driver at that time. He finished in the top 10 23 times, with his best finish in 2nd position in 1969 at Milwaukee.
Malloy died as a result of injuries sustained in practice for the 1972 Indianapolis 500. During the practice session, he was attempting to break the 200 mph speed barrier (which other Indy drivers were trying to do at the time) when his car mysteriously cut sharply to the right and crashed head-on into the outside retaining wall at about 186 mph. He died a short time after being pulled from his destroyed car.