Can I use wax or polish on matte paint?

No. Matte paint gets its flat look from a micro-textured surface that scatters light. Waxes, glazes and polishes fill or flatten that texture and create shiny, uneven patches that are difficult or impossible to reverse. Use shampoos, detail sprays, sealants and coatings specifically labeled as matte-safe, and never machine polish matte paint to remove scratches.