It'll almost certainly be packaged in the MAS file. File structures aren't open like they were in RF1 and need extraction.
I've found it, thank you. But there is a problem. if I want to save the edited mas file, ( Vehicles .mas ) --- I see this message ( when game started) "Core component Vehicle v.2f is missing, invalid or demaged Unable to continue. Please reinstall rFactor2" what am I doing wrong?