Mine certainly folds up, and there are signs of just that happening, but there isn't a sharp crease in it. I've been told that the soft windows should be carefully cleaned before putting the top down, in order to minimize markings.
One day when I replace the top, I'd like to go with a solid window, but I've heard that the Firebird needs a two-piece like yours had. That doesn't seem like a real good idea, but I've never actually seen one...
I've also "heard" that some modifications must be done to the car if you want to install a one-piece glass window. Hopefully someone else here has some knowledge about this...
