Frog11 - the factory color is a pasty grey - not flat black. I've tried a number of products on mine, but have not been totally happy with any of them. It is nearly impossible (at least in my experience) to get an even appearance. My last attempt was to use rubbing compound and wax. Better, but still uneven. Maybe someone here will chime in with a product that has worked for them.
If you don't like the color, the best thing would be to paint it or have it painted. As I recall, they are very expensive from Isuzu, and you'll end up with the same thing.
"If you're not living on the edge --- you're taking up too much space!!"