So my 1er suffered from common vent discoloration. I don't know if this is from sun fading or some other cause. I just knew I needed to fix it. Starting at it all day cheapened my ride and drove me nuts. Soo... I took a bottle of Mothers Back to Black and a foam Q-tip and went to work. I will attach a before photo below, as well as an after shot. I did 3 applications, let them sit for 5 minutes and then wiped away.
3 weeks later all of my vents still look brand new.