Now for a question: what on earth is the point of the piece still hanging off of my bus (right)? As far as I'm concerned it was a pine needle collector and a pain in the rump to clean when giving my bus a bath. The only reason it did not come off with the bumper was that it is hanging on to some pretty rusty metal and needs some delicate attention.
That flat metal on the bumper ends is a splash pan............ since the corners of your bumpers are round..... Vw put those there to keep rocks and road debris from smacking the rear corner of the bus.......it hits the bottom and spins around the curve to hit the paint........

They do help secure the bumper too.....