I have one hard wired into my daily driver. It's a Nextbase and is good, you can buy wiring harnesses from eBay cheaply so you can wire it to be on only when engine running etc or permanently on for theft damage etc.
The only issue with them is, mine included, it doesn't record well at night, some of the more expensive units have a night vision assist. The other issue is playback, the supplied leads only connect to computer and then the view is small, the patch leads to hook to TV on mine are very expensive and not as yet available 3rd party.
Don't judge but my missus is a Police traffic officer and they are finding them more and more helpful for the innocent party, mind you she thinks we are all guilty.