This was apparent a couple of months ago, when we had a daily race at SSRX.
I brought it up in this forum, and while there didn't seem to be any disagreement that it was happening, there was disagreement about the cause. Some folks think it's because of weather conditions. I believe that the game was not giving me identical cars for each session.
Human elements are eliminated in the first two sectors at that track. It's just straight line driving. Before I even got to the starting line, I could make the decision to proceed or kill the session, based on where I was when the car shifted to 4th gear (A/T). Wind speed and direction were static for each session.
Also, and I don't know if it's because the cars we used there were rented, oil degradation came into play. Somewhere in the range of 2 1/2 to 3 1/2 laps into the session, you just started slowing down for no apparent reason. Your ghost would just start pulling away from you, while going full-throttle down a 6 mile straightaway.
At the beginning of November, there's a Nations race at SSRX. Do your analysis there, if you want undeniable proof.
I'm not a great driver, but at the Daytona Tri-oval daily race, I finished the week at #2 in the world, and at SSRX, I was #1.
I'm not that lucky.
I just saw what was happening. You can bet your ass that people like Jeddah Racing are aware of it too.