Jerry knows a lot more than I do about what goes into the programming behind the software versions, but I will say that the bluetooth issues are not present with iPhone and Samsung phones used in the same vehicles. Some companies are further behind in security and updates, but those two are generally pretty up-to-date. I am hopeful that Google can and will fix the bluetooth issues or I will be selling my Pixel XL.It definitely does suck. If the audio can be fixed that would be good... BT isn't really a fix since as Jerry said if they used older technology in specific vehicles that is less secure that isn't really Google's fault.
At least it is better than my last high end phone that could possible burn / explode on me .