GoPro, non HD versions have ok quality and cost nothing. The HD version is the ultimate, but cost a little more.
Hit the on button, make sure you have the movie icon up, hit the record button. Red light is flashing, you are recording. Pretty easy.
Comes with a suction mount, drop that on the interior light / inside windows. Nice vision.
http://www.racerecall.com/
These guys are in Moorabbin.
John