[mikefocke]

And put a clean fleece cloth between the plastic window folds so they don't rub together. After you have cleaned both sides of that plastic with something like Novus 1, 2, and 3. From an older posting:

Rear Window

We have all seen discolored rear windows on convertibles. They don't have to age like that. Mine is 5 years old and looks like new but it wasn't like that 2 years ago when I bought the car. It was discolored and cloudy. And the surface was rough.

Novus makes a series of products designed to deal with the problem (if you already have it) and to prevent it in the future. The Novus 1, 2 and 3 products consist of bottles of plastic cleaners in decreasing levels of abrasiveness. The three products are sold in a kit with several microfibre polishing cloths for about $25.
If the top is new, only use #1. But if the top is already discolored, you start with the most abrasive cleaner, Novus #3, and a clean rag (I use a cotton washcloth) and you rub it on the surface as if you are polishing the window. Do the outside of the window first, then do the inside. Keep it off the top (but if it gets on, just wipe it off quickly). Let it sit for a while. And then take another clean rag and polish it off. Then do the same using the mildly abrasive #2. And finish up with the non-abrasive #1 which is more of a polish than a cleaner. You should only have to do this once.

In addition to cleaning and polishing the surface of the window, these products seem to put some sort of oil into the plastic that allows them to increase their flexibility and thus resistance to cracking.

For maintenance, I use Novus #1 about once or twice a year.