I would HIGHLY suggest a clear bra; my boss has this on the front, headlights, door handles, sides, and back of his viper and on the front of his vette.

I bought my XF used (and black) so there are a lot off rock chips up front. I polished and waxed that car which helped a little, but after i get the bumpers repainted, i am putting a clear bra on ASAP. Tomorrow I get the headlights and foglights done on my car!