These sharks tried to get me to pay for a scratch on the front fender when I returned the car. Here’s the scam:

On check-in they work at a snail’s pace (missing required forms, needing to confirm vehicle info.) then once your thoroughly frrustrated and ready to sign anything put an end to the Keystone Cops routine, they suggest you take pictures of any noticeable damage - that is not already documented. I( I took 10 photos including an odometer shot. They had a windshield star noted on my rental document.)

On the return, it’s they Tom and Jerry show all over again, but now you have a plane to catch, and don’t they know it. When your number is finally called, they doddle through the process like it’s their first time. The clerk inspects car and his first question is “did you take pictures of the car before driving off with it?” I assured him that I did, and showed the series. He said my photos were too far away to show the damage he found (a 1/2” Long scratch on the hood, and the windshield star) . He also tried to ding me for excess km usage. After a series of arguments he offered to reduce the charges to just hood scratch, like he was doing me a favor. At that point the commentary got pretty colorful, end with me jogging to departure in order to barely catch my flight after refusing to sign their damage claim document.
Two other people on my flight relayed similar stories, and I have found multiple complaints similar to mine on the web that follow the same pattern. It appears that this type of scheme is common with Sixt. This was my first - and last - time renting fro Sixt.