Holy crap man, what kind of "car" do you have? Must be an suv or something.......
Anyways, most car monitors are for VGA, meaning the resolution is pretty fine for displaying text, etc.
An lcd monitor that you would use to display, for example, a television broadcast, is not as "precise".
Now, if you only want to display video's on the rear monitor, I don't see an issue.
Getting it to "flip down" and look halfways intergrated might be a different story........
As might be to power it.
Also, that avatar is quite disturbing!