Mother's Back to Black works OK but not perfect, and you have to keep reapplying it. I finally took off the flairs, sanded them, and painted them with flat black bumper paint. They look like new after that. Well worth the effort and not expensive at all.

As for the bumper crack, I now have a huge crack in mine since I forgot the cargo trailer was still attached one night. Yep, I backed around and hit it with a sickening crunching sound. Made a big dent in the left rear body, too. I've never feltmore stupid. For what it's worth, I found that a toilet plunger can help somewhat with large dents.