Harry Arminius Miller (December 9, 1875 – May 3, 1943) was an influential and famous American race car builder, most active in the 1920s and 1930s. In the opinion of noted American racing history Griffith Borgeson, Miller was "the greatest creative figure in the history of the American racing car".
Cars built by Miller won the Indianapolis 500 nine times; three more instances were won by his engines running in other chassis. Miller cars accounted for no less than 83% of the Indy 500 fields between 1923 and 1928!
If Offenhauser engines, a re-badged Miller derivative, and the dominant engine at the Indy 500 and on the Champ car circuit in the 1950s and 1960s (although it kept winning until the 1970s) are added, the number of wins at Indianapolis alone increases by 28, with over 200 more elsewhere. It was not until 1981 that an Indy 500 start did not feature a single Miller-derived engine.
Miller started off manufacturing carburettors for passenger and race cars. His involvement with the racing side of his carburettor business led to repairing and later building race cars. After repairing the 1913 Peugeot Grand Prix car which was the state of the art at the time, Miller and his employees, Leo Goosen and Fred Offenhauser designed the Miller racing engine from the Peugeot layout. This began a thoroughbred line of race motors that dominated American racing well into the 1970s. Miller went bankrupt in the 1930s. Fred Offenhauser purchased the shop and continued development of the engine through the 1940s and 1950s as the Offenhauser or "Offy" engine, selling out to Meyer/Drake in the 1960s. Parts for these Offy/Millers are still being made to this day.
- He was named to the National Sprint Car Hall of Fame in 1990.
- He was inducted into the Motorsports Hall of Fame of America in 1999.
- He was inducted into the Automotive Hall of Fame in 2003.
- Mark L. Dees, The Miller Dynasty: A Technical History of the Work of Harry A. Miller, His Associates, and His Successors (Barnes, Scarsdale, 1981; second edition Hippodrome, Moorpark, 1994) This is the definitive work on Miller, but was published in limited editions, and may be hard to find
- Griffith Borgeson, Miller (Motorbooks International, Osceola, 1993)
- Griffith Borgeson, The Last Great Miller: The Four-Wheel-Drive Indy Car (SAE, Warrendale, 2000)
- Griffith Borgeson, The Golden Age of the American Racing Car (Bonanza, New York, 1966; second edition SAE, Warrendale, 1998)