I use Simple Green and a light brush. Then a high quaility vinyl and leather restorer from a auto detailer shop. Anything with Armoral is a total no no. Many of the products on the market claim a one step cleaner/protector/UV etc etc and are geared for the short termed look good fast and easy crowd. Long term effect is faded, brittle and cracked vinyl. You want your seats to last. Go to a professional detail shop and check out their product line.
fatrap