Can you post exactly which car you have selected, if you use any upgrades for it and which track-layout it is?
Car is - Kodi - 2005 Rayzor - Kodi Factory Team - Kodi #61 -
I am only seeing this when racing through the Race Season - Lienz Festival of Speed 2006. I do not see this happen in any other modes such as Testing or Race Weekend.
It does appear to be tied to the upgrades. After you asked I went through and tried a few different variations, and was able to see it went away depending on different upgrades installed.
I can make it happen if I choose RC1 and select Suspension - Stock Suspension. There are other variation I could choose and get the same issue, but many others make it go away.
I am running these setting and seeing it:
Rear Wing - RC1
Front End - RC1
Rear End - RC1
Tires - RC RS-GT
Suspension - Race Suspension
Brake - RC1
Hood - RC1
Exhaust - RC1
Flywheel - Racing Flywheel
Competition Kits - Production Class Kit
Differential - Adjustable Differential
I upgrade to the "National 4WD Competition Kit" and now it is gone.
Unlikely there are many people out there that would see this I suppose, but it is an issue I do not remember ever seeing with my disk install. Since installing it through Steam I've been replaying through all the base mods without cheating trying to get all the cars fully upgraded. Just a personal challenge.