The news that wireless Android Auto will only work with devices running Android P might not be totally true. Oreo might be supported as well.
Android Auto Wireless Will Work On Android 8.0 Oreo Smartphones
Google has confirmed that Android Auto Wireless will also work on Android smartphones running Android 8.0 Oreo. In its initial press release, it stated that only devices running on Android P would support wireless Android Auto. However, Google has since changed that. Meaning that most current smartphones will work with Android Auto Wireless. However, you