> When Android Auto loads up, it shows me a tile with the current weather. In Fahrenheit. I want it in Celsius. Everywhere on my phone I've set it to Celsius. In the Settings (I think multiple ones). In the actual weather app. But AA will show it in Fahrenheit.

I don't think I ever saw this behavior?

> Why is there always a navigation app loaded?

I think this is the default? I have OsmAnd+ instead of Google Maps by default.

> It eats up too much battery. Why does it need to eat so much battery if all I'm using it for is to listen to podcasts? With regular Bluetooth, it barely consumes battery.

This is because your phone needs to encode the contents of its display as h264 stream.

> Why does the air vent fan speed drop dramatically when I get a call? Why does the climate system even know I'm getting a call?

AndroidAuto can notify the car that it wants reduced noise.

> That's all from the top of my head. I'm sure I can come up with plenty more.

This is all fixable in software on Android. Nothing from your list is a problem on the _car_ side.

Given that the protocol is now documented and available, it doesn't even need to be implemented in Android. You can have a KDE desktop running on your car!

I actually played with that about 10 years ago: https://github.com/Cyberax/aauto/tree/master