This an issue with the mics in the mirror design. (not that the mic is defective). The placement of the mic is on top of the mirror and somewhat away from you. Because of this, you need to speak a little more projected than you would if the phone was at your head. This also why there wasn't complaints with the Jawbone ear piece.
Kind of like when people are on speaker phone, you hear a lot of other sounds and the person doesn't sound so great. You would probably get similar results if you strapped your phone to the mirror and placed a call.
In the Wrangler, Jeep has gone to the mic in the headliner area, near the driver sun visor. The complaints have gone down drastically about bad sounding calls. They need to consider going this way with all the vehicles.
Originally Posted by tnjeep
My windows are up, sun roof closed, and AC has been off up till lately but people still complain about the noise. Used a jawbone up till I got the jeep and the calls sounded fine with it. I'm not sure what could be done about it by the dealership unless they tried replacing the microphone/rearview mirror.