I've heard quite a few people complain about how much the built in microphone in upper trim 2012's sucks. I can attest to this; at freeway speeds you have to scream at it to get it to understand anything you're saying. It's also virtually impossible to make a phone call as whoever you call thinks you're driving through a tornado.
I've devised a very simple (read, inexpensive) solution to this problem. It involves shoving sound deadening material in the space above the microphone to reduce the amount of ambient noise it picks up.
Video of how to do this is here
It worked wonders for me; now I don't have to burst my lungs in order for it to play a little Stevie Ray Vaughn
You may wish to use more material than I did in the video; I added more after the first test run and it helped quite a bit.