If you want to really customize your own, you might make one with a Raspberry Pi.
As youd expect, this setup has a few bells and whistles.
It has two cameras, a forward facing one and a rear facing one.
It also has GPS packed into it so the camera always knows where its recording.
Sure, most of us probably dont need all this, but its a fun project nonetheless.
A Raspberry Pi Dashcam| Blogspot