In this video I install a circular polarizer filter on my G1W-H dashcam to help reduce reflections seen on the windshield.
You will see how to select the right orientation on the filter, and also sample footage during both day and night time.
34mm to 37mm step-up ring
37mm Circular Polarizer filter
G1W-H car dashcam
BlackVue DR400G-HD for comparison footage
The video was recorded with my OnePlus One smartphone – I think it did a decent job.