CPL in front of dashcam lens kills 2+ stops of light. so definitely NOT used
and moreover I have a CPL only for panoramaS and it could not be fitted with the panorama2
passed some tests = "lights killed by CPL at night" a couple of years ago, so I do not recommend using CPL 24/7
just asked because i was wonder: the reflection in panorama2 was less then the other in these pictures. And in my experiment, the dashcam has far distance from windsheild will have more reflection then the ones has short distance from windsheild. Maybe i was wrong.