Just ordered and received a small container of Gtechniq I1 Smart Fabric. Intend to used it not only in the car soon but also on the kids boots, (& mine as well) when winter rolls around again.
Will chime in when I get it applied in the cars.
Have been using it lately on my dark grey Altima and like it. I use the Microfiber Blue Towel, aka: Woobie.
Which appear to be similar to Griot's Speed Shine Micro Fiber Cloths. (Wish I had a Black car to try this combination on.)