sounds like my 02's window has the same issue. looks like someone rubbed a little too hard to get something off the plastic at one point in its former life.
I use Plexus, and use it liberally. Seems to help, but does not last more than a couple months (daily driver, in Florida sun/heat/humidity every day). Big can lasts a while.
I am still searching for a "paste" for the center of the window (fold area) to see if I can get that to look better. (a neighbor told me BMW makes a good product?) I also tried 303 from Marine West store and had about the same result. I believe Plexus and 303 are similar products?
Spray on the plexus, let it soak in a bit, soft towel dry it (don't use micro towel- it's a little too abrasive INHO.)
when I start really noticing the scratches I usually just drop the top
