They are well marketed, but suck in actual use. OK if you use them outside on the hood, roof or front splitter, but then you get no audio. I've had better luck with a $20 suction mount and my point and shoot canon SD770 mounted to my windshield. I eventually plan to upgrade to one that takes HD video.
lots of examples here:
https://www.youtube.com/daign
Here is a link to the $20 mount.
http://www.amazon.com/Panavise-809-C...?tag=amaz98-20