Please mail your comments for now. Different auto manufacturers use different mounting methods. Our mirror mounts to the rectangular style buttons found on most domestic vehicles. European and Japanese vehicles use two styles of round buttons. There are a few options for you if your car has a round button.
Adapters are available for both styles.
Buttons can be removed from the windshield and changed. Finally, a new button can be glued to or below the existing button. North may not be North. Magnetic North can be as much as 30 degrees off of true North. You must tell the compass what declination zone you are in so that it can compensate for it.