This idea may be old hat for all of the pro's, but here goes. First,I sterilize(as in,cleaner than new) the wheel wells. I use HOT water and Spic-nSpan,with a brush.Next,I wipe them with denatured alcohol,several times,till the rag comes away pretty clean.Then,I mask off the plastic pieces and the outer lip of the wheel opening(fender).I use the wide blue masking tape,doubled,so I have a tape lip around it.Then I spray the wells with semi-gloss chip guard.(black).The chip guard has a good film thickness.It's texture looks like what they put on at the factory.I use two cans for the job.Peal away the tape.Juice up the plastic parts with a silicone based dressing that I got at a local detailing shop.The wheel wells look better than when the car rolled off the assembley line.Nice,crisp,and black.