Now I've refitted my two passenger seats I might hold off on retrimming for a while as I think there is a huge improvement. The only problem is the seams are wearing thin. I might get another years use from them. I haven't yet washed the drivers seat, so stripping that is next. In the photo, it's not a shadow, it really is so much darker/dirtier than the passenger seats.
If you've not done this, I really recommend it. It makes a huge improvement and it evens smells nice
