After a challenging few years without any race driving, Simpson was back in a full time race seat in 2014 driving for JDC-Miller MotorSports in the Tudor United SportsCar Championship. The highlight of the season was a 3rd-place finish at Road America. In 2015 Simpson raced in selected races in the Tudor United SportsCar Championship and finished 3rd at the Daytona 24 Hours, 2nd at Detroit and had a Pole Position at Lime Rock Park. During 2015 Simpson was also a race driver for LAP Motorsport, the official team of MINI USA.