I run the G1w dash cam. It can record anytime it sees motion 24/7, or ignition only. It has pretty good quality.
Only downside is when the memory card is full it stops recording and you have to push 2 buttons to format. So maybe once a month I have to format. Some of the other cameras record over old footage to where you never have to mess with it.
G1w is 1080 at 30fps or 720 at 60fps.
As far as running 4 that is a lot of wiring and cameras in the car. I could see running one in the front and one in the back on motion but 4 is too much.