I seriously considered the Road Hawk system. I was finally put off it by the need for the 12v external supply, the associated trailing leads (which I don't like) and because it needs to be fixed in the car, so isn't easily transferable from car to car.
I finally settled on a Sony HDR-AS15 as I decided I could do without all the data logging systems. It has good battery life and so is easy to transfer between cars. The image quality is excellent, especially when using the image stabilisation system. The sound tends to be a bit muffled because I use it in the waterproof case on a a screen suction mount. It may be worth consideration, but one point of caution; when I was rear ended in France a couple of years ago, a front facing camera would have been of little use... other than to record the jolt!
I got mine from here:
http://www.dogcamsport.co.uk/All usual no connection/interest points apply, just good service. They also sell the Road Hawk as well, plus others.
Oops! Overlap with Adrian's post - both recommend Dogcam Sports Cameras though!
