Stefano, I use the cleaner-wax exclusively on my white car, and it cleans and protects quite well. Most purists will scoff at a 1-step product, but I have found that the quality of the product is far less important than how often you actually use it. I can wax the car totally with my orbital buffer and the cleaner-wax in 20 minutes. This encourages me to do it more often, thus better overall results than the once-a- year 5-step process.

Of course a black car is a bit more demanding than a white one, so it depends on your particular circumstances. one hard rule however, unless you are just gently waxing a perfect (new) surface, USE AN ORBITAL BUFFER. They are SO easy and fast, and never ever swirl. In 20 years of maintaining a black car, I learned a lot, but the most important was to never hand rub it with any kind of cleaner, always use the non-swirling orbital.
okay, soapbox back on the shelf. Have fun.

Cheers.