Even a pressure washer can’t remove this stuff. It looks like grayish dust or maybe road tar that’s stuck on the wheelwells. There are also some asphalt specks that hardened on the paint on some areas. Is there a solution or chemical that can remove this without damaging the paint or undercoat? Thanks in advance!
I also tried scrubbing it with an abaca scrubber (I’m afraid the paint will get damaged if I use a more abrasive one) then blast the dirt with a pressure washer, but when it dries off the gray stuff is still there
yes it’s not the rustproofing because dealer said they didn’t apply any rustproofing to the underchassis.