Im scheduled for a log call today at about 1 PM PST. This means they're aware of the issue and critically working on it.
From my hardware/software experience as a developer, it seems that the bluetooth protocol (basically the way the bluetooth chip is programmed to communicate) is too new for most car systems which usually come with bluetooth chips that don't really focus on higher-rate higher-quality audio connections; which is what the iPhone 7/7+ is transmitting. In other words, the iPhone is sending bluetooth frequencies that are way too dense for the Bluetooth receiver in your cars to understand, causing a freeze (speaking on behalf of BMW) because of an overload of data.
If my research is correct, the iPhone 7/7+ comes with Bluetooth 4.2, which is backwards compatible all the way back to Bluetooth 4.0 if the iPhone is transmitting in Low Energy (since 4.0 is when the Low energy tech was introduced); and backwards compatible all the way to Bluetooth 1.1 if it's transmitting in Basic/Enhanced data rate.
The question now is, does the iPhone 7 transfer audio data through Low Energy?
• If Yes, then our BMW's need to have at least Bluetooth 4.0.
• If No, then our BMW's can have any version of Bluetooth starting from 1.1 (Which is almost guaranteed).
Another question is, Which bluetooth protocol does BMW use?
This seems to be an issue with cars (BMW only) dating all the way back from 2014, and Bluetooth 4.0 was first implemented around 2010-2011. Therefore, your BMW is probably using Bluetooth 4.0 (I may be wrong). That being said:
iPhone 7/7+ (whether transmitting in Low Energy or Basic/Enhanced Data rate) should be compatible (hardware wise) with your BMW.
So what may be the issue? The iPhone software may not be properly recognizing the BMW's Bluetooth 4.0, and therefor sending data (audio) at the Bluetooth 4.2 rate (250% faster than Bluetooth 4.0); which is much higher than what Bluetooth 4.0 can handle (10 times the data capacity).
Just my two cents. Thoughts?