I use the one shown below, bought off amazon. You do need a micro SD card, and the dash cam itself is $70 with the SD card about $10. I used another brand dash cam that did not work for more than a year. The AUKEY that we have now has excellent video and night video, and loops to record 3 hours +, with writing files over itself unless you want to hit the save button or there is an accident and it saves automatically.
We have 5 of these dash cams, one for each car and the RV. Yes, there are fancier units with rear view, but this version worked for us. There are cheaper versions, but that bit us as I've said.
Thankfully we've never had an accident and needed it, but I've saved a few near misses that had the heart pumping.
Search this on Amazon and check it out. Highly rated, good quality so far.
AUKEY Dash Cam, 1080P Dashboard Camera Recorder, 6-Lane 170 Degree Wide Angle Lens, Supercapacitor, G-Sensor and Clear Nighttime Recording