SEM brands make a prep spray that is very useful when painting vinyl and plastic interior parts. It chemically " cleans" the part and lets the paint adhere much much better than just spraying the paint on. You may have to go to a shop that sells paints and paint prep products to body shops and such to find it. It can be found in spray cans as well as in bulk as I recall and its not expensive. Mikey 62 Crown Coupe