I have a black Avalanche and have been using Zaino products for the last 5-6 years or so.
http://www.zainostore.com/ I found out about their products on the Vette forums like someone above had said.
It sounds like alot of work if you read their application instructions but the stuff goes on and wipes off extremely easy. They polymer based and hold up extremely well to the elements. Much longer than a traditional carnuba based products.
The Z-6 and Z-8 smell good enuff to pour a glass and swig them down :P
I have no relationship whatsoever to zaino, their products rock, check them out.