After much fumbling around trying different products, I've finally settled on using carnauba only. On my black car, I went from using
Klasse to Zaino, back to Klasse, then back to Zaino...and now I'm using P21S (w/ no polymer base).
Of course, if I didn't live in So Cal or any area where it hardly rained and never snowed, I wouldn't consider anything other than Klasse or Zaino.
The next test for me on black will be the new BF