When staying in Germany on a temporary basis (e.g. as a tourist), you are permitted to drive a motor vehicle if you have a valid Australian state/territory licence together with an official translation into German.
Translations of Australian driver's licences can, for example, be obtained at the ADAC, a German automobile club. Please make sure to submit your original (!) Australian driver's licence to an ADAC office in Germany or send it by registered mail to the ADAC at the following address: