Hmmmmm, I have so many favorite car soaps...
BLACKFIRE Wet Diamond Conditioning Shampoo- Designed to work with any BLACKFIRE LSP, from BlackICE to Midnight Sun and everything in between. Since I usually use BLACKFIRE products on black, this is probably my number 1 choice.
Duragloss 901- The budget-friendly super soap.
1Z Einszett Perls- Still, IMO, the glossiest wash n' wax product available. Water will bead off your glass for days.
Ultima Paint Guard Plus Shampoo- Super Slick with Amazing Rinsing.