Hello FlipNJ,
I did test Pol filter an my SD59430U-HNI... but dont find the sample pictures. Sry.
I glue on all my SD59430U-HNI an UV filter (same, what is used für DSLR) some mm bigger, as the lense, over the lens, and so I have on all cameras (because of the thread on the UV filter), the possiblility to use all kind of DSLR filters. Also Pol filters.
What I can remember was, that the car windows (that was the reason for me (like for you)) were visible, BUT, like on DSLR, the Pol filter takes you brightness away (like a sunglass), and because my SD59430U-HNI are none starlight cameras, I prefer a better picture in the night, than having clear and visible Car windows.
Hope I can give you some information to decide... give it a try, and you will see my findings.