lower door panels and rocker panels on 1998 GTP

i, maybe i'm in the wrong forum here but always kept this car in basement original paint still excellent except for lower door and rocker panels..both sides have become faded and tarnished..what is the cause of this when rest of original paint is excellent?

Let me guess, it's a black car?

Either way, it's likely just the ABS plastic getting old and causes the clearcoat/paint to go with it or possibly the paint color. My brothers 01 GP has the exact same issue yet my dark blue 2000 GT does not (and no, they have not been repainted and it has lived 85% outside for 24 years and 500K+ miles.)

Could be the jsut clearcoat failing on it and making them cloudy as well. I'm not expert on the paint but have seen it multiple times. Might be able to buff it back out with compound and polish.

Ford man is right. The material that the claddings are made of is too old now and the deterioration shows through the paint. Unfortunately there is no simple solution. The material is unlikely to be strong enough now to survive removal, refinishing, and reinstallation.Hence, replacements are no longer readily available.

Headliner material is also nearing the end of it's life expectancy at this point and the upholstery is no longer as supple as it once was. It is a matter of elapsed time and materials used. UV exposure merely accelerates the degradation. After the plastic all dries out and the paint on it is cooked, a thin spot in paint at right front corner of roof is the next place to show.

All of these cars are well past the age they were designed to endure.

my 2003 GT 4 door, has the same issue with the lower door moldings, the car is Red.
Covered in garage.
I use wd40 and the color comes back but has to be done one a month, however, not the solution.
The both lower Rocker panels, have been re fabricated, with Fiber glass, and re painted factory "Victory red"
​NOT CHEAP !! But looks great.

yep..its black

thanks man for your reply..