P4 requires unlock when in car

Yes I have. Thank you. Still no worky.

I may return the phone for a new to see. Apparently, this has been an issue with select phones going back a year. The support community at google.com have been reporting it for a while with no fix from Google.
 
Ugh, it's probably just some bug related to Bluetooth connections to cars. Most likely, all you can do at this point is to send them feedback and hope they fix it!:-\