He won the 1980 and 1983 USAC Dirt Track champions in a Silver Crown car.
A crash at a Championship Dirt Car race (AKA Silver Crown Car) in Syracuse, New York on July 2, 1974 crushed his left arm and left it paralyzed. He regained enough mobility to drive but never fully recovered from the injury.
Bettenhausen competed in Champ/Indy style cars from the mid-1960s until 1996. During this time he won six USAC Indy Car races. He made 21 starts in the Indianapolis 500, contesting each event from 1968 until 1982 (with the exception of 1979 when he failed to qualify), and again from 1986 to 1993. His best finish came in 1980 when he finished third after starting 32nd in the 33-car field.
In the 1972 Indianapolis 500, Bettenhausen led 138 laps (of 200), and appeared on his way to victory. But he suffered a blown engine with only 24 laps remaining, and dropped out to finish 14th.