Just washed my car and got off all of the salt/grime crap form the recent snow we had here. While drying the car off, I noticed what looked like small surface rust spots on the rear license plate. At first I thought it was just the plate but then I noticed that it was all across the lower portion of the hatch. It looks like a little piece of material on the surface with discoloration around it. Any body got an idea as to what this might be?
I read the post concerning clay bars and rail dust, but this car has 18K on it. I'm thinking some sort of pollutant/contaminant.

 

Industrial fallout, rail dust, acid rain....they go by different names, but clay bar takes care of all of them.