I thought that piece encircled in yellow is metal, not plastic and would have to be color matched if faded. Sounds like a lot of trouble and expense. Is it really that noticeable? Obviously it's yours to do what you want but mine's a little older than yours (being a 2014) and I'd put the money toward ensuring mechanical reliability or toward new tires or emergency/unexpected repairs before spending it on faded spots. Probably not the answer you want to hear but just my perspective.
Nothing wrong with taking care of your car. You are correct, that is plastic. I just checked with a magnet. No big surprise since everything seems to be plastic these days. For some reason I always thought it was metal. Anyways, on my Liquid Silver CX-5 the roof always looks duller than the rest of the car. Not noticeable from ground level but viewed from above the contrast is noticeable. Even while waxing/ceramic coating where I'm right on top of it, it never achieves the gloss of the rest of the car. Been that way for ages. Minor gripe.
The tops of cars collect a layer of fallout/buildup more so than any other area. It over time compacts into a hard layer than doesn't come off with standard washing. It benefits from decontamination (chemical + clay bar) to remove it and restore the paint.
I understand what you're saying. Last fall, prior to applying 3 coats of ceramic wax, I gave it a good rubdown with polishing compound followed by alcohol wipedown. The polish made an improvement but I figure it's as good as it's going to get. Or as good as I'm going to try. Don't want to try rubbing compound on the clearcoat. It's not horrible by any standard but duller when looked down on from above. It's just the large center section, the narrow section visible at ground level that runs from front to back across the top of the A,B,C pillars above the doors is glossy as the rest of the car.
