+1 with audio interference using Bluetooth on my iPhone 7 plus model A1784.
Did complained to apple that sent me a new phone (same model number) and still happens the same, or even worst then the previous one.
Did several tests lately, first with my carrier (Vodafone Portugal) in two cars I have, 2011 Audi A6 with MMI and also a Jeep that has a Pioneer SPH-DA120. And both have interferences in certain locations (in dense city areas). But always the same spots, when in 4G mode. If i switch to 3G the interference disappears.
I also have interferences with a bluetooth headphone Sennheiser MM 550-X. Is really annoing.
I should mention that I don't notice any interference when in rural areas, or smaller cities. (i drive everyday 110 KM). Only in medium/big city like where I live (Porto and Matosinhos in Portugal)
I've contacted my carrier, that said it's not their fault. But explained to me that their antennas in big cities operates in different frequencies compared with the rural antenas. And this might explain the above. They also suggested me to try with a different carrier GSM card, since my iPhone is sim lock free and bought directly from apple.
And that's what I did. I bought a pre-paid sim card from MEO carrier and still happens the interferences when in 4G. On different spots from Vodafone, but i think is related to the places where GSM Antennas are located.
I tried as well with my sim card with an old iPhone 5 i have with same ios, and the interferences does not happen in both cars.
I explained all the above to apple support, i hope my examples makes them understand that this is a serious issue, specially now iPhone does not have a headphone jack, and they want us to use bluetooth.