I originally bought a cheap one which did not work. So searched on the internet and found Ipxi in car cameras. They are located in Surrey. Very good pre-sales and after sales service. Not cheap but not had any problems since I bought it. Works off the cigarette lighter socket but can be permanently wired in. Fits on the wind screen behind. Can take the small chip out and view where you have been on your PC. the mirror so cannot be seen when driving. Hope this helps.
Hands-on: Samsung Galaxy S8 review