I fitted my dash cam this evening, 10 minute job!
Not the best test as it's dark, first impressions is the microphone quality is rather dire by the sounds of it, but I must admit this is straight out of the box and you can adjust the configuration on the PC, so my recordings from snetterton should be 10 times better both Audio and Video wise...
I have set it to 1080p and the highest bitrate available, 12Mb/s i think it was off the top of my head.
The below video is 720p at 4Mb/s
You can also attach an external mic, i think the reason the inside mic is bad is due to it being a small unit it is against the casing and vibrates a lot as it's fixed to the window.
http://www.youtube.com/watch?v=cHksDzOWP7c&feature=youtu.be