The black streaks are not random. They seem to follow the seams on the roof. My problem is that the streaks are actually under the rubber. This is a left-over 2016 model and sold to me as 'same as brand new". The dealership tried to clean it last week and it would not come clean with all of their chemicals.
At the time of purchase I was physically unable to look at the roof and told "everything was all cleaned up and ready to go". I didn't notice the roof problem until a few weeks later.