Hello, I found those strange artifacts. the first time i saw them was 15 june 2018 rFactor2 latest version Windows ver. 1803 nvidia driver ver. I dont' know i7 860, GTX 770, 8GB,
Read this and the next post from Tuttle, that explains what it is. https://forum.studio-397.com/index.php?threads/strange-shadow-crossing-the-car.60306/#post-948455