Well I don't own a black car but you should be able to feel the slickness while applying and removing reload off the surface.
You would be using Ech2o as a drying aid to help with avoiding water spots.
Good video on the incredibrush.
https://youtu.be/OzFfK2ifvw8
Another on the EZ brush.
https://youtu.be/xsXkqhfs-Mc