I found out which HD2 texture is “responsible” for the color / brightness of dust clouds behind driving vehicles. On desert night maps these dust clouds are way too bright and reveal the vehicles too easily.
The file is named hits.tga
If you open it with a viewer or editing program, you see on the lower left side of the map a kind of transparent sand cloud.
I tried to edit it, but tga files are a bit tricky. The effects were all gone after saving the tga file.
Maybe somebody can to try to edit it, and make the sand field darker and maybe more transparent?
Btw you can have some funny results if you take another tga file and rename it to hits.tga