I haven’t found a serious test yet, except for ADAC and Autobild(ok manyicht not so serious 😉 ). There is a rich selection of miracle remedies. Especially those with alleged ceramics or even Teflon as “active substances”. I have heard that some even damage the engine. What experiences have you had, what do the car manufacturers say about it? Less consumption, even more power or all nonsense (as I suspect, otherwise all nee already delivered directly with a coating!). First of all thank you for your opinions!