I've found a number of similar questions. However none of them are an exact match, hence I need to ask this.
I just found out that my grandmother in Germany has passed away and I would need to travel this Saturday (today is Tuesday AEDT). Unfortunately, my Australian passport expired May 2017. I am aware that the Passport Office has priority service, however as the passport number changes and you normally need the number to book in the flight, I won't be able to book the flight in time.
I am a German dual citizen and have a valid German passport. I am wondering if I can leave Australia with my German passport? I know themat once I am in Germany, I can go to the Consulate Office and apply for a 6-month emergency passport, so I'm not concerned about coming back. But it's more whether Australian immigration will let me leave.