I had my old El Camino ceramic coated as my first test. It is single stage paint like the 911 and as a high mileage (370,000 miles) daily driver has recently gone for many weeks at a time with no wash job due to weather.
I just did the checkbook version. A local guy uses Mr. Beasly's product line. His process is to clay bar the old dirty paint, them do a power buff, and wash and then he starts on the ceramic coating. He also detailed the entire car inside and out but I told him to leave the engine compartment alone except to hose off any dust. He does the door jambs and tail gate area, and cleans the wheels, and uses Bon Ami on the windshield. All for $550 for the Elky. It made it a LOT shinier.
I liked the results a LOT. I brought him my baby, the 911. The interior was clean and needed little more than clean the windows. He did clay bar it, and then put on the ceramic coating. It did not get any more shiny, but it is easier to wash and keep clean. I drove 900 miles to my brother's house in Alabama. He asked it I stopped and washed it before I came over. All I did was drive throughout a heavy downpour in Mississippi and that cleaned all the bugs off. The 911 was just $450 since it was really clean to start with and it is a small vehicle.
We even had my wife's 2018 Macan coated. It just makes it easier to clean the car.
I just came in from washing my El Camino. We have been in a cycle of a little rain every few days, and it was fitly nasty gross for my standards. Today was mid 70s so it was just too nice to not clean it up. The weeks of dirt and grime just wipe off with minimal effort. It has been over a year since I had it coated.
Overall I highly recommend it if you like a clean car. I do know it takes a lot of work, and I am too old an lazy to try it. My money was well spent.