Google has announced that it will no longer support Android Auto updates for phones running Android 8.0 or lower.
As of the latest Android Auto update, version 15.5, devices must be running Android 9.0 or higher to receive updates.
Phones with Android 8 will no longer receive updates, with the last supported version being Android Auto 15.4.
According to Auto Evolution, the system requirements for Android Auto have changed to require a device running Android 9.0 or higher.
Author's summary: Google ends Android Auto support for older phones.