Originally Posted by Xan

Could be the bottle, I did find that the first coat is the hardest to buff out.
Any coat after goes easier and that spraying some Z6 in between helps as well.

I fixed all the swirls before applying any Z5, so I can't really testify whether the hiding works. But I can believe that it probably doesn't do much.
I just use it to layer it, as I found my paint looked a bit flat with just Z2.
In your case with a black car I'm sure flat paint is not an issue...