For black cars best wax to use IMO from it being used on my car and seen on other black cars....Pinnacle Souveran.
http://www.pinnaclewax.com/souveran.html
Heres a pic thats 2mths old from the previous detail job Rob did for me. This is a raw photo, no editing. Only thing Im not a fan of is the paint job a shop did on the front bumper, seems dull compared to rest of body.
I really want to repaint the whole car something else, black is just to much to deal with down in florida with all the pollen, dust, other crap. Im leaning towards a lambo/new viper green possibly lol...time will tell.