Friends, the skin of ATS in F1 mod always shines ever under the rain in cloudy weather.
The texture is noticeable at night, as well as some individual details of other cars.
How to fix it?
Screenshot:
These will help get you started. But actual procedures may vary depending on what graphics program you use (in some cases I've had to use two different programs to deal with rfactor graphics for a single car). A search for "alpha channel" and "rfactor" will disclose more.