Thanks for the question. I understand you are experiencing issues connecting your iPhone 5 with your car via bluetooth. The following article may help to resolve your issue:
I thought there was a problem with the unit in my car too but there isn't.
PLEASE NOTE: I am not in my car, this is from memory.
What you need to do is use the head-unit navigation wheel(it can also be pushed up, down, left and right, not just a scroll wheel like some think) to navigate to the bottom left of the screen where you see a message like "bluetooth is open and ready". You will find and option there which will then start searching for your iPhone. This is where i got confused also, as I though I had to search for the head-unit from my phone but it is your head-unit that you use to search for you iPhone.
You need to have the bluetooth on on your phone and on the cars head-unit you need to find your iPhone and select it. Once done, it will prompt you to input a password, enter something like "0000", doesn't really matter but once done you will get a prompt on your iPhone at which point to enter the same code again, "0000" in our example case.
I know this post is old but I'm sure another person will have the same problem we all did.