Sedan Rear "Grill"

It's called a diffuser, but go to the link at the bottom of my post. I've had mine sine October and it hasn't faded, but mine's also always garaged.

Exterior Trim Products - Detailed Image

Use mothers "back to black"

^^ I would recommend Mothers too.

^^ I would recommend Mothers Back to Black as well since it's what I use. Next time you wash the car, take a microfiber cloth and with your soapy water, give the diffuser a good scrub. After you've dried your car and you've got all the water out of the gap betwen the diffuser and bumper, use some B to B and a soft cloth and rub it into the diffuser. Wipe it smooth and even and then you're done. You can go a couple of washes now without having to redo it if you remember to wipe it dry after each wash.

Cheers.

PS. check out the video of my rear LEDs and you'll see a diffuser that was just washed but no B to B this time. I've had the car 6 months and have over 17,000 kms on it already.

http://www.forteforums.com/forums/body-kits-appearance/1320-led-tail-signal-light-info-2.html