I have a mk6.5 Fiesta not a Fusion but thought you guys might be of some help anyway? I had no luck in the Fiesta Forum
My Fiesta has been in my family since new and has always had the creaking/ squeaking sound coming from the C pillars. We went to Ford multiple times when the car was new and recently when I took over the car I decided to try again with independents but no one has seemed to be able to fix it.
The only solution I have is to give both pillars and the roof lining above the C pillars a little push every time before driving and it usually sorts it, but sometimes this doesn't even work. There is one side that makes more noise and is also looser when pushed than the other.
I have tried stuffing it with rubber seals and felt to increase tension and taking the clips off the panel to release tension and spraying WD40 - none of these worked
Has anyone else had this problem with their Fusion or know of a way to fix it?