I have one in my commuter car, need to add a second one for rear facing and also add one to the truck and my wife's car.
I was going to get one with front and rear facing in one camera body but after hearing of some camera having one channel dying before the others, I figured it would be better to just get 2 inexpensive ones.
I have a $60 cpacitor model I bought off ebay (have to look up the brand/model) that has been doing good for over a year now. Uses a standard mini SD card.
I keep the mic off most of the time, mainly because if somthing happens nobody has to hear my singing before the incident............