What is the best shampoo for ceramic coatings?
Quick answer: Use a pH-neutral, coating-safe shampoo with no waxes or strong detergents. A plain maintenance shampoo is fine; a SiO2-boosted shampoo is a nice-to-have, not a need. Avoid harsh alkaline or acidic cleaners and TFRs as your routine wash, and pay attention to technique.
Any proper car shampoo is fine on a ceramic coating. Modern car shampoos are formulated to lift traffic film while staying close to neutral pH, so they clean without attacking paint, trim or the coating sitting on top. There is little meaningful difference between the mainstream brands on the shelf.
Many shampoos contain a wax for extra shine -- the "wash'n'wax" type. These will not harm your coating, but there is no real point in laying wax over a ceramic coating, and the residue can dull the hydrophobic behaviour you paid for.
You can also safely use quick detailer, dry wash and waterless wash products, though some of these may affect your manufacturer's warranty, so check the small print before switching away from a normal bucket wash.
Most people are not hunting for a specific brand name. They want to avoid using something that strips, dulls or shortens the life of their coating. You have more headroom than the marketing suggests -- but you do need to stop reaching for the heavy-duty stuff every weekend. Buy a pH-neutral, residue-free car shampoo from Halfords, an online motor accessory shop or the motoring aisle at your local supermarket and you will not go far wrong. As long as it is made for cars, the differences between the mainstream products are small.
Things to avoid as your weekly wash: strongly alkaline TFRs and all-purpose cleaners, acidic wheel cleaners used on bodywork, household washing-up liquid (the degreasers strip protection over time), and anything that markets itself on "cutting through" wax or sealant -- that is exactly what you do not want on a coated car. Stronger chemistry has its place once in a while when traffic film has genuinely built up, but not every weekend.
Shampoos with a splash of SiO2 can top up slickness and give a short-term boost in beading. They will not magically extend the life of the base coating, but on a car that is a year or two in, they are a nice way to freshen things up between maintenance visits. Do not pay a huge premium for them -- they are a top-up, not a replacement for the coating itself.
Technique matters more than the brand on the bottle. Even the best shampoo cannot protect against dirty wash mitts, brush washes or careless drying. A two-bucket method, a clay bar once or twice a year for bonded contamination, and clean drying towels will outperform any upgrade to a premium-priced shampoo.
For more on washing technique and what coated cars actually need, see how to wash a car with a ceramic coating.