I am having a car kit for my Motorola V60 installed tomorrow and am unsure where the glass mount antenna should be placed so that it doesn't effect the Nav or Radio reception. I am using the Terk Dual Band CFR-904 antenna that looks like a computer mouse, ideally I would like to center the antenna on the rear window.

 

A cellular antenna is so small, I doubt it would affect your NAVI reception. Since I believe everything for the NAVI is contained in the box that is under tha package shelf in the trunk, to play it safe you can either mount it in the center or on the passenger side.