I have one of these;
Garmin Dash Cam 20 review - CNET
It's note the cheapest but the resolution is good, even at night. Date, time, speed, gps location are all recorded with the video. When you look at the video on a computer, the app shows your video on one side of your screen, and brings up google maps on the other side with a dot showing your location and it moves as the movie plays. Quite impressive.
When there is an impact, the amount and direction of the G-Force is recorded and shown on the screen.
There are cheaper ones if you want just video, but I like this one.