This was probably one of the more difficult things for me to clean. Recently I ordered some Interior Shampoo Gel from AG With their small scrub brush and man does this stuff work. Spray it on the seatbelt,scrub with the brush, let sit for a little bit then hit it with a steamer and a brush attachment. Finally wipe down with a terry cloth and appreciate the clean seatbelt! Thought I would share with you guys in case someone was looking for an effective way to clean seatbelts.