Since I do not use the monitor in the car but in my Bastelkeller as test monitor I use a 12V power supply to the power connector from the power supply was OK so I have the included power cord is not used and had to rewire anything.
The image on the monitor is good for the size of the display. While 480x272 is not HD and today's smartphones have the same large display with a much higher resolution but MMN is the resolution good enough and the picture is not unpleasant verpixeled.
All in all, a good monitor. Whether 5 inches (Current smartphone screen size) must reach each decide for yourself ...