My family has a 2012 Toyota Highlander w/JBL stereo that utilizes bluetooth for handsfree calling and playing music, much like what many other vehicles have these days. So this might be of some insight to some. The issue described within this thread has been helpful to me, not only as confirmation that it's not only a problem for me, but that it's not limited to Toyota or JBL as it seems.
The specific issue I'm addressing here is: after you power off your iPhone running iOS 6.0.1 the pairing will no longer connect between the phone and car stereo. The iPhone w/iOS6.0.1 shows the device, but won't connect when the car is on. Only way around this that I found was to delete the stored pairing and start over, trying not to power off the iPhone to avoid a repeat of the issue. So with this issue, being frustrated about it, I started with JBL stereo company and was directed to Toyota factory head unit support.
I contacted Toyota support yesterday to try and diagnose further into if they are aware of this bluetooth issue and if they have a firmware update in the works (i was hoping). They acknowledged the issue as known, and also noted that they have tested iOS 6.1 (not released yet as 6.0.2 was just released) and as far as Toyota knows, this update is to include a bluetooth fix which effects Toyota users. Toyota did not mention anything about other car manufactures, or when Apple would release information about this or a fix or iOS 6.1 update. I'm assuming Toyota can only act in behalf of themselves when saying things like this, so I hope this is understood.
So I'm just trying to relay information that I was told on the phone by calling this Toyota support number - 18003314331
If you Toyota owners question the validity of this, call and ask yourself. I just got tired of scouring the forums for an answer and I will wait for Apple to release an update at this point, whenever that happens.
Cheers!