> nor does it affect Android Auto which is a "dumb" screen mirroring protocol with the bulk of the software running on the connected phone rather than the head unit

Huh, how does that work anyway? And while we're at it, Apple CarPlay as well? Both can run wirelessly via Bluetooth, but BT is nowhere near capable enough to stream full bandwidth video?

Wireless AA and CarPlay use a hotspot your car emits that your phone connects to and transfers the image/inputs/audio that way

Wireless CarPlay uses Bluetooth to exchange SSID and key info before switching over to WiFi for the duration of the session.

They didn't run over BT. BT is used to initiate communication and share the password to a wifi-network. It then uses that Wi-Fi network for most communication, keeping the BT channel strictly for telephony.

The way I understand it, the connection is negotiated via BT, but then wifi is used for the fat data pipe to run the display.

I thought the latest Bluetooth protocols were basically designed to hand off to an ad-hoc Wi-Fi connection between the two devices after the initial handshake. (Might be an oversimplification of the real protocol)

They actually run over WiFi (WiFi direct IIRC) - Bluetooth is mostly just used as a setup handshake and to help the head unit decide which phone in the car should be the one connected.