 The following year, he tested a car for Mullins Racing at Daytona International Speedway; he was 56th fastest.He continued racing in his home state at the Madison International Speedway events in 2018 and 2019 with Fast Track Racing Enterprises, finishing 18th and 16th, respectively.In August 2019, MBM Motorsports announced Karth would make his NASCAR Xfinity Series debut with the team in the CTECH Manufacturing 180 at Road America; with Karth at the age of 66, MBM stated their pride in being a "gateway for so many racers, young and old, to accomplish their goals."