The car is a white Toyota Camry 2012.
As you can see there are many tiny black dots on the roof. I can't remove them by scratching by hand or with a high water pressure cleaner.
What caused these dots? What can I do to remove them?
The cause can be one of many possibilities:
or worse paint overspray
The first two should come off - good cleaner / polish and lots of work, but the paint may mean that you need a re-spray at the worst - there may be a professional treatment that could do it. So go and see a good paintshop and see what they say.