I have paint bumpers & other things. All I do is scuff it with 320 grit. Any more finer & it will not stick or any more coarser & the scratches will show. Clean with a wax & grease remover. I always spray an adhesion promoter on it.
silver w/ met. black but not sure about the hood it needs to be wider to match the trunk lid & maybe a 1/4 inch red pin stripe between the silver & black just a thought good luck with it