I recently purchased this item from an ebay seller in china and I’m very impressed with its image quality – easily good enough to show who was a fault in the event of an accident (in view)
http://www.ebay.co.uk/itm/200949401657?ru=http%3A%2F%2Fwww.ebay.co.uk%2Fsch%2Fi.html%3F_from%3DR40%26_sacat%3D0%26_nkw%3D200949401657%26_rdc%3D1
With the addition of a 4GB memory card, I have a fully working dash cam for less than £23.
On highest quality recording, the 4GB can handle 2 hours recording, after which it is overwritten.
The unit has too many features to list here, and as usual with such things, the instruction manual is not very detailed.
Personally my major concern with such a thing in the car is that the local crims will think it is worth lots and break into the car. Therefore when parking almost anywhere in public, the camera has to be removed and hidden from view.