Ideas... check out Dash Cam Talk forum.
Generally when it comes to the mirror type, they are usually battery instead of capacitors for high temp locations. Also mirror type is limited on features regards to the menu and user settings.
I've run mirror type, camera w/suction cup type and stick-on wedge type. Keep in mind although mirror type can do 2-channel (front and back cams) usually the back cam is of lower resolution. But if you don't run a front and a separate rear cam, then I guess the 2-channel mirror cam is a good compromise. The mirror type I tried had it's display centered within the mirror. If I had to do it again I would have the display to the left or right side, but that's just me.
Also some have chrome look around the lens, easy to spot. Either go black or take a sharpie and knock the chrome.
Anyway check out the forums as some of them folks are in the know.
Also read into the micro SD cards. Many cams have a type, brand and limit size. Check out for firmware updates and do routine format.