Usually American soldiers and military personnel are exempt from local policing. In Germany, they couldn’t be stopped for a traffic control or asked to identify themselves by German police, only US military police. There even was a guy that got away with murder because of some related issues.

Here’s the story:

https://www.lto.de/recht/hintergruende/h/acquittal-despite-confession-wittlich-us-court-martial-justice