Concerning the mesh grill I was wrong. Everything is ok and nothing has to be done. If you see the first pic on page 1 of this thread when the car was almost new the mesh is bright, the two last pics taken recently show that the mesh has darkened by aging during 2.5 years. It was not only the light which was responsible, I saw it in the metal again yesterday and the mesh is darker now in the way I like it.
