Vanthoor was named on the entry list for the final two races of the year at the former Formula 1 venue on Tuesday, but has backed out of the weekend at the last moment to concentrate on testing the Porsche 936 LMDh car for 2023.
The 31-year-old has been named as part of the Porsche Penske outfit that will compete in both the FIA World Endurance Championship and the IMSA WeatherTechSportsCar Championship next year, although it's not clear which of the two series he will race in.
