While the purpose of all these paint protection treatments aim to protect the finish of your car as well as to enhance the shine, all these elements do is to 'sit' above your clear topcoat for a period of time.
But before we progress, allow me to define the subject matter at large.
Pros: Liquid waxes are easily applied over the top coat of car paints to provide a glossy finish. Paste variations may require more effort due to higher carnauba content as with added compositions.
Cons: Usually lasts no more than a week or two, depending on your UV exposure and climate. Being oil based, wax generally attracts road dust after some time.
Pros: Liquid synthetic sealants are easily applied over the top coat of car paints just like wax to provide a glossy finish. Generally, they last longer than wax and do not attract so much road dust as they are often synthetic and not oil based.
Cons: Require constant re-application to retain the UV and acid rain protection. Higher quality sealants may come costlier than most conventional waxes.
Pros: Nano coatings last longer than conventional polymers like sealants and repels water much better. Higher UV and acid rain protection and more resistant to conventional cloth swirls from regular washing.
Cons: Requires proper paint surface preparation and treatment (IPA wipe, machine polish and clay depending on surface condition) before application. Top coats must be completely smooth, grime and watermark free prior to application. Best applied by professionals and is very costly. Doesn't bond forever and requires a 6~12 month re-application to maintain the UV protection and shine.
Creatively, most nano coating applicators preach that their products are actually made from glass and that they have a scratch resistance of 9H like Gorilla glass or something. Some will go on and on and play down the competition, swearing that a certain made "Glass Coat" from a certain country is the best and that others are knock-offs. Some applicators charge S$800 and up with 'guarantees' that these glass coating will 'bond' for years!
As a trained mechanical engineer, I find this really amusing but sad that many innocent customers fall into paying the high dollar for fictitious claims thinking that they had their paint coated with glass!
BUSTING THE MYTH
2. If this was clearly glass as they say, wouldn't it crack if someone were to give your bonnet or door panel a hard slap? A regular door dent at the parking lot would perhaps seem pretty much like a bullet hole if the door panels were indeed coated with glass? Do give it some thought...
Nevertheless, what some of these nano coating manufacturers are referring to is nothing more than a so called "Pencil Test" on polymer films. In simple terms, the coatings, when cured as a polymer sheet, can resist the scratching from a 9H pencil under a constant given force. This implies that the coating is indeed a polymer and is certainly not glass...
So the myth is totally busted...
THE HARD TRUTH
Nano coatings are not glass or ceramics. They are just a better polymer!
Humorously, one applicator tried to hard sell me the idea that only their magical "Glass Coating" had a "Self-Healing" property and that applied heat with a heat gun by their specialists would remove light scratches. In theory, this would be 'true' because these nano coatings are polymers and they will all likely behave in this manner as explained by the glass-liquid transition theory. As do epoxy and other industrial polymers, polymers soften with heat and is no surprise. To soften glass, you would probably need a blow torch, a big one!
As I said, waxes, sealants and nano coatings all work but the cost vs benefit can only be justified according to the requirement of the paymaster. So study the pros and cons before deciding. Jump into it if you must but do it with your eyes opened for a better judgement.