Products that come to mind from a concours guy - Vinylex. Spray on, let it sit, wipe off excess with wet sponge. Somewhat expensive, though. Also try Meguiars rubber and vinyl restorer. Works very nicely, same technique. Most all products that enhance the black will add slipperyness based on the approach you are taking. Now if you want to recolor the seat (black), there are products that do this but are more permanent and more xpensive.