I just joined to share an experience. I have a 2008 G35 and, probably just like yours, found the dull black paint on the door plastic was slowly being scratched and scraped away. I lived with it for many years until I decided there must a a solution. I found one.

I'll spare you what I tried that didn't work...including going to my autobody guy who said he could do it but then, on seeing the plastic pieces, said they probably would not withstand their primer.

Frustrated but not yet quite ready to give up, I then went to the local Ace Hardware and they mentioned spray-on Krylon Fusion. I didn't buy it then but instead went home and got on their website (https://www.krylon.com/en/products/all-products) then got in touch with the company customer service people. They were excellent. Got all my questions answered. I'd recommend you contact them too, if only to build your confidence! Basically they told me exactly what is printed on the can but also suggested things I hadn't thought about, like lightly sanding with 220 first and carefully cleaning and drying the pieces

I went back to Ace and bought the black satin finish version, since it approximates the texture and color of the paint I was removing. I also bought two pieces of 220 sandpaper that easily bends for that light sanding.

Then I had to remove the old paint. To remove it I used a chisel edge and lightly scraped it off. It didn't take much for it to come off. ( I'm sure any hard, straight edge will do, preferably metal. Probably not a knife.) I was careful not to scratch the plastic...that would have been easy to do had I pressed too hard--and it's difficult to hide scratches under this paint. (Everything seems to show up in the dried, finished product.) So sand a bit more and get all the scratches out, if there are any, before painting.

I'm not great with spray paints, seriously, not great at all. But this stuff worked really well. The four door plates I needed to repaint all look great. Here's my story...

I started with the front door plates. My insecurity caused me to move while spraying more slowly than I think they recommend. So the finished paint ended up being slightly thicker and glossier than I expected but I'm okay with that. I put on 3 coats too, though I see now I didn't need to. Why risk mistakes or bubbles or dust, etc?

(Note: Don't rush. Take the time to let each coat dry according to the can instructions before adding the next one. It's just a few minutes. When finished, let sit overnight and see if you like what you've done. If not, it's easy to sand it off and start again or touch up.)

On the second day, I then did the two back door plates. Now confident, and again in no rush, I moved fairly quickly across the plastic and it laid down very evenly and completely. That finished texture is more the satin I was looking for. Very happy about that too.

Why Fusion? I was told I needed a primer on the plastic. Fusion is made just for things like this because it contains the primer in the formula. It also sprays quite evenly and lightly and can be sprayed evenly at angles. Plus it dries fairly quickly so you can add the 2nd coat without waiting too long. After use, the can requires no special cleaning either.

I let my finished products sit for 2 days to complete the final drying, once I was sure I liked my results. I then reinstalled them.

I just had to share this, probably my first successful spray paint experience in my 76 years. I hope it goes as well for you too. And, if you're like me, you really will enjoy the look of your G35 interior much more.

Oh...final tip...do yourself a favor and keep your leather steering wheel and seats looking good and supple by using Honey Cleaner and Honey Conditioner. The best I've found. https://www.leatherhoney.com/

Bill

 

I think 220 is a bit rough for painting. Some of the scratches might still be visible after the paint dries.

But post some pictures of your work!