Fitzgerald ran two races in the Winston Cup Series, both as a road course ringer at Riverside International Raceway, in 1986 with Bobby Wawak's team, and in 1987 with Hendrick Motorsports. In the 1986 Winston Western 500, Fitzgerald started 35th and finished 39th after completing 29 of 119 laps due to issues with the clutch. The following year, in the Budweiser 400, Fitzgerald started 37th and finished 17th, two laps down. The race made Fitzgerald the oldest driver to run a Cup race at age 65, a record that would stand until Morgan Shepherd ran the 2013 Camping World RV Sales 301 at age 71. Fitzgerald had planned to compete in additional Winston Cup Series races for Hendrick during the 1988 season.
