Indycar (FR US Cup) became slower in Mid-Ohio challenge

I started to play the challange with the Indycar (FR US) in Mid-Ohio. The last time I played, was this afternoon. Now (about 6-7 hours later) the car is simply much slower, however I haven't changed any settings. (The top speed at the end of the start-finish line is ~25kmh less) Now, it doesn't make any sense to play, because I'm 5s slower in every lap.
Do you have an idea, what can be the problem?

 

Check your pedals, maybe you aren't hitting 100% throttle input anymore.

 

Or there's a loose connection so you're trailbraking the whole lap.