Given the fact it seems to be coming from the middle of the car, and it almost looks like a normal map coloration pattern, I'd also say it's not skidmarks.
And the devs start off the year with their token coffee pic. http://www.beamng.com/threads/micro-blog-s-2017.34617/#post-510425
and we now have a crew cab. check that off the list. still need that long bed version of the D-series
http://www.beamng.com/threads/development-screenshots-2.24313/page-2#post-511514 Long bed would be nice but I understand it's probably a lot of work.
So that explains the Steam Branch in which you update the test branch with all the goodies and stuff for the next updates.