If you want a "good paper" to understand the behind mod injection failures and race conditions in game modding:

: Typically C:\Program Files\SimBin\GTR Evolution or similar.

Navigate to rFactor/GameData/VehicleFilter/RI_Global_12110.FILTER . Open it in Notepad++. Do not copy-paste the whole block. Instead, add only the specific line for your new car's class.

Go to the game’s mods or addons directory. Delete only the folders related to the extra car pack you’re reinstalling—e.g., car_pack_extra , custom_cars , or numbered car slots. This avoids duplicate entries.