Can I use a rinseless or waterless wash on a ceramic-coated car?

Yes, for the right level of dirt. Rinseless and waterless washes rely on lubrication to lift light dust and grime, and a slick coating helps them work. They are not suited to heavy mud, grit or salt crust, which can scratch both coating and paint when wiped. Use plenty of product, several clean microfiber towels, light pressure and single-direction wipes, and switch to a full wash with rinsing when the car is genuinely dirty.