Audio through phone speaker when charging via car usb

It sounds as if the USB port you used in the car was there to use an iPod, or you could use your iPhone for the same thing, This is especially true if the port is near the radio set, or has something written by it. Many cars have multiple ports, one for connecting a media device, and one for charging. I would check to see if there is another port, or take a look at the owner's manual. The issue was not the iPhone, but the car's port.

While I realize that having a charger with you can be a pain, trying to understand different vehicles can be just as bad. I know this may be a bad example, because the car has CarPlay, my wife's Hyundai has one port right under the radio, and that is what connects it to CarPlay. There is another port in the center console, and that one is strictly for charging purposes. My car has two ports in the center console, one for connecting it to the media for the radio (I don't have CarPlay in my vehicle) and the other is just for charging purposes. And of course, not all manufacturers make their cars the same, and tend to leave off an explanation of what the port is for. Good luck.

I appreciate your thoughts. I agree about those that are not tech savvy. However, I believe the issue here is the fact that you have connected to the headphone jack of the iPhone with the car, and with that thinking, there may be a way. If you open Music, and are looking at what you are listening to, I wonder if you can tap on the song you are listening to, so it comes up on the screen individually, then look at the icons on the bottom of the page. The center icon is a small triangle, surrounded by a few circular lines. That is the audio selector. If you tap on that, it shows what you can use to listen with. I wonder if you can select the iPhone rather than the car. I cannot test it here now, but maybe you can try it next time. Good luck.