My setup is iPhone 4 and Bluetooth in my 2012 SUV.
I have a 80 minute highway commute. I have real trouble hearing the other party at highway speeds around 65 Mph or higher.
If I drop my speed down by 15 Mph, I get much clearer voice quality. The phone shows me either max bars for connectivity or 4 bars in either case.
This leads me to believe that it is not the Bluetooth, or the quality of the phone itself, but the quality/strength of the signal captured.
This is the only reason I am considering switching phones. The iPhone 5 for AT&T has the 4G LTE network.
Is voice quality better because the 4GLTE is a faster network? Does the quality of voice issue at high speeds go away for the LTE phones?