Picking up the car in Berlin was very convenient; it was just a few meters from my hotel in the city center. They offered an SUV upgrade for an additional 5 euros, which was nice, but since my driving skills are average, I decided to stick with a smaller car. The staff at Hamburg airport were quite indifferent, and they closed earlier than other rental companies on the 31st, at 4 PM, though my scheduled return time was 4:30 PM. So I returned the car through self-service and hope there are no other issues.