The US PPL only allows you to fly US registered aircraft worldwide.The requirements to convert your license are different.
Please check the requirements for your home country with your national aviation administration office.
Acceptance in Germany
Minimum of 75 hours logged flight time Second class medical certificate in accordance with JAR FCL 3 AZF or BZF I/II or validation of US radio operator license Certification in "Immediate Life-Saving Measures"/First Aid Pass a theoretical exam on airmanship, human performance and limitations Official 'O' or 'P' certificate Report from the German Central Register of Traffic Offenders in Flensburg (form) Background checks (ZÜP) in accordance with German law (LuftSiG) Flight review or check ride with instructor or examiner Application form (L1-007.03/99) from the German Federal Office of Civil Aviation (Luftfahrtbundesamt)
Conversion to a full JAR-FCL license
Minimum of 100 hours logged flight time (as of August 2004) Further documentation as noted above for acceptance procedure A check ride (Annex 1 JAR-FCL 1.130 and 1.135 and Annex 2 to JAR-FCL 1.135) If the license has been accepted and you already have 100 hours of logged flight time, no additional theoretical examination is required, but you must complete a full PPL check flight with an instructor designated by the district government. When you successfully convert your license, you will automatically acquire a CVFR qualification as well If you want to fly at night, you need additional night flight training in Europe You can use a European flight school for this training.
Important facts for international customers: 
