Read through this thread on autogeek but beware of the proselytizing.
https://www.autogeekonline.net/forum...stic-trim.html

Then pick a store (auto parts, amazon, autogeek--wait for sales) and get a good all-purpose cleaner, stiff scrub brush, and the protectant or coating of your choice.

I've used the Chemical Guys All-Clean with good results. I'd also suggest 303 protectant as a relatively inexpensive option. Also works good on interiors and doesn't slime over like Armor All.

 

Carbon Collective Trim coating
https://www.carboncollectiveusa.com/...h-free-t-shirt

I put it on my flares a year ago, it's been through a ton of washes and it still looks great.

 

 

Mother's Back to Black. Use it often and it will last longer and longer. I use it on most of the cars i detail, and it's one of the few OTC products I use.

 

Black Wow is pretty amazing. I used it on my 2011 countryman. The black looks great. Its expensive, but a little goes a long way!

 

Black Wow Pro - buy a little bottle. get some foam makeup wedge sponges to apply it.It lasts for a long time and goes on pretty easy. you dont need much. I also use it on the JCW painted parts of my aero kit and it matches the arches.

 

I'm a huge fan of Aerospace 303 protectant - especially for plastic trim pieces like this. It really makes the edges on my '13 Countryman shine. Plus it's a strong UV protectant so it keeps them from fading. I've had good luck with it (and it's a popular choice on auto detailing forums). What I've done in the past with already-faded trim is use Mothers Back to Black, then follow it up with Aerospace 303 to keep it shiny.