I was more curious if it was gouged out or just a faded black plastic turned grey.
If its the latter, I have used Bondo's Restore Black on my Isuzu Vehicross with great results. It takes a time or two to get it even, but it looks good and has held up great for a year or so. There are many, many, many black plastic restoration products out there and most of them suck. I'd follow what people with Chevy Avalanche, Pontiac Aztecs and Honda Elements say. Those have more faded black plastic than anything else.
There's also this method:
