Rudy and Ann Hoerr became part of auto racing as car owners and builders when the old Mt. Hawley Speedway was operating in Peoria, and they went on to become an important part of the national racing scene for many seasons. They moved from local racing to regulars on the United States Auto Club's (USAC) stock car circuit, then a rival to NASCAR for big league status, and later competed in both the International Motor Sports Association (IMSA) and the Sports Car Club of America (SCCA), both national organizations that race from coast to coast.

Once they became established in the USAC stock world they put big name drivers in their cars, Peorian Herb Shannon, Bill Chessburg, Bob Christy, Billy Foster and four-time Indy 500 winner Al Unser. Foster also competed in a number of Indy 500s until fatally injured in a Hoerr stock car in California in 1966. Unser, just starting to make a name for himself in Indy cars, spent six seasons in the Hoerr stock car, producing five wins while driving both Dodges and Fords for the Hoerrs.

The Hoerr sons, lrv and Scott, were sponsored in IMSA competition between 1975 and 1978 and lrv began a brilliant career for his mom and dad in 1979, first in IMSA and then in the prestigious Trans-Am series in 1988 through 1991. He won season championships in 1986 and 1987.