It appears to be on a round-the-world flight and has been noted visiting parts of Western Australia and New South Wales over the last couple of weeks after arriving into Australia via Darwin on Thursday 3 August.
D-EGAC was later noted departing Gladstone Airport for Cairns.
Meanwhile, passing through Central Queensland airspace also on Thursday 17 August was another Piper PA-46-310P Malibu Mirage on a round-the-world flight. It flew from Townsville to Archerfield.
The aircraft registered N662TC took off from Kiel-Holtenau Airport in Germany in late July with the flight around the world raising money for Dr. Reijntje’s School for the Deaf in Sri Lanka (http://www.schoolforthedeaf.lk).
You can follow the progress of the flight at their website: http://www.zahorsky.net/blog/