1) You wouldn't want to simply add another mic for the passenger, the vehicles that use 2 separate mics have electronics that will pick up voice from one mic while limiting noise from the opposite mic. It's actually a lot more involved than that but the explanation would be long and quite technical.
2) You wouldn't want to place the mic near the rear view mirror. You'll pick up more road noise as well as defroster whoosh when it's being used due to air being forced up the windshield. Most vehicles mfgs have moved away from the mirror mounted mics.
3) If the top wasn't removable, you could extend the wires to the mic and mount it to the headliner area in between the driver & passenger just in front of the shoulder distance from your windshield.
4) you could try a dash mounted location toward the middle of the dash.
Of course this would be trial and error and take a little time for comparisons.
Originally Posted by Capt Jack
Has anyone come up with a solution for how to improve cell phone mic pickup? My last car had 2 mics - onbe for driver, one for passenger - it worked great. My 2014 Unlimited Saraha w/ UConnect 430 has one mic, at the A Pillar on the driver's side. So, the passenger cannot be heard. Can a 2nd mic be added over the passenger side? or can the one included be moved to the middle, around the rear view mirror?