Nothing will really take the scuff out. A little Armor All on the bumper trim will probably cover it up and make the rubber appear to all one tone. If that doesn't work Mothers sells a great product for car trim (anything which is an exterior plastic, rubber, or vinyl on a car or boat) called Back to Black. It costs about $5.00 and works wonders. The trim does not need to be black to use it either, it can be any color. It basically removes oxidation, helps with scatches & scuffs, etc.