Feel for you mate..........like you say you do your best to keep the Z scuff and dent free, but it always seems to draw the dumb, mindless couldn't give a s--t drivers to it. Like others have said a couple of hundreds tops for repair.......or like WhackyWill said, maybe get quote from dent/chip removal guys. They charge so much per panel and looks spot on. You can even take your car to them and they do it while you wait ( a few hours) but least you get car back that day........either way all the best and you get your great Z back to pristine A.S.A.P