We black car owners deserve a sainthood when trying to keep them clean and shiny - it' s a nightmare [

] but then black is the best colour.
Over the years I' ve used three waxes:
Starting off with the cheapest, Turtlewax Black Colour magic. This is less of a wax and more of a polish. To my eye it does give slightly the best finish, and fills in the tiny swirls, scratches with black shiny stuff. But....it doesn' t last very long. expect to reapply every fortnight on a daily driver. An £8 bottle lasts me a year.
I was given a pot of £80 Zymol Titanium wax. This stuff lasts absolutely ages (up to six months) and smells lovely, but it is harder work to apply. For best results use Zymol HD Cleanse to polish your paint and remove any imperfections before waxing (this smells even better [

]). I estimate this pot willl last me 10 years.
I' ve recently been experimenting with a small sample pot of Raceglaze (bought from an open day at Cornbury house) on my blue car. This seems to be similar to the Zymol regarding wax content and easy to apply like the Turtlewax. It generally lasts two months before I need to re-wax.
So my conclusion - Don' t bother, within two hours a black car looks filthy again [

] so just drive the damned thing