Glare

[JeffIan]

So you really don't think the marks may just be very well caked-on gunk?

 

[Nigel]

So you really don't think the marks may just be very well caked-on gunk?

I think they are of too high optical quality for that, and they would have bigger halos, plus you said "I tried Fantastik just to see if the marks would budge.".

It could be that there is gunk inside the scratches.

The light streaks/arcs are significantly longer than we normally see, so I'm not quite sure what the issue is.

If you want to remove them completely, get new glass.
If you want to try and decrease them, then use some glass cutting polish and quite a lot of time.
Or you can live with them, you have been looking through them without complaining until you got the camera, but they were there since you got the car. The camera image is quite good and detailed, other than the light streaks. Some professional photographers go to a lot of effort with starburst filters to get effects like that!

 

[JeffIan]

I appreciate very much your detailed answers. I agree that for the time I will live with it. I purchased the dash cam for safety purposes not for picture-taking.