Was able to book a car last minute for a multi-day trip. Was pleasantly surprised to find that I got upgraded when I arrived. Lars was very professional, friendly and spoke great English.
The car was great for my trip, we were allowed to take our small dog and got all the information we needed. There was a small problem with one of the parking sensors, but Lars cleared this up and put it into the contract to avoid any problems later on. Everything to do with the condition of the car was very transparent and clear. The vehicle seemed otherwise just like new, no complaints.
When returning, there were no places left in the SIXT bays at this location, but the employee was very understanding and said it wouldn't be a problem. I unfortunately didn't catch his name but he was Lebanese-German and really had great customer service skills. I would definitely say this was true for all people I spoke with at this location.
It's pricier than other options, but you get what you pay for. I would use SIXT again and can only recommend.