One sure way to find out what causes trainer issues is to verify if the trainer/game versions still match.
The game got patched since our trainer release and is at least on v126.96.36.199 now.
Please use the update notification system to report a game patch, update or to report that the trainer may not be working with the latest version of the game. If 3 or more reports have been filed, consider BOOSTING the priority of this title for a faster turnaround on the updated trainer.
You will need to update your game. The latest trainer we have is.
1. Project CARS 2 Trainer 188.8.131.52.1056.AVX