He retired from motorcycle racing at the completion of the 1961 season and turned his attention to auto racing.
Leonard raced in the USAC Championship Car series in the 1964-1974 seasons, with 98 career starts, including the 1965-1973 Indianapolis 500, sitting on the pole in 1968 in the Granatelli turbine car. He finished in the top ten 60 times, including 6 wins: 3 times at Milwaukee (1965, 1970, 1972), and once each at Ontario Motor Speedway (1971), Brooklyn (1972), and Pocono (1972). His victories propelled him to the 1971 and 1972 USAC Championship Car Season Championship.
He is the only American to win the national championship in both automobile and motorcycle racing and in 1991, he was inducted into the Motorsports Hall of Fame of America in the "Motorcycles" category.
Indy 500 results
|1968||Lotus||Pratt & Whitney||1st||12th|