I have used Harly Wax on my black car a couple of times during the past year. I like it a lot. It's very easy to apply and remove: I waxed the entire car, did the swipe test and discovered the wax was ready to be wiped off. It leaves a balanced warm carnauba shine. Beads nicely, too. I'm not sure about the durability, as I didn't push it to the max, but it was still going strong after 5-6 weeks when I polished and waxed the car.
It's a great price ($20 plus shipping). It comes in a nice large 14 oz. tin. As I recall, the shipping cost is the same for two tins as for one. I may be wrong about that, though.
Harly Wax, IMHO, is a solid, under-rated carnauba wax. It is well worth trying out.