Before going to a replacement, you may try to polish them, using a light paint polishing compound and an electric paint buffer.Sometimes you have the impression that the color is fading, but actually it is the surface that is getting dull. If you can restore the surface to its original shine, it improves a whole lot.On my sedan, the tail lights were also looking old. I took them out and noticed that there was blackish dirt layer on the entire internal surface. I filled them with warm water and soap, let them stand for about one hour and then rinsed with warm water and let them dry completely. Color improved a lot by doing this. Then I buffed them down (the outside of the lenses)and put them back in place. Amazing-They looked like new again and were of course a lot brighter. That was 2 years ago, and they still look great. I do not know if it´s easy to remove them in the SW and whether the inside washing is viable, but I guess it is.