The car pickup systems at the two Frankfurt airports are not interconnected, which is not a great experience.

When returning the car, we forgot to fill the tank and specifically asked the staff if we'd need to pay extra for not returning the car with a full tank. He said no additional charges would be applied, even after we asked him three times to confirm. However, after we returned home, a high fee was charged to us. Make sure to return the car with a full tank.

I am still waiting for my updated receipt, having had to take it for an extra day.

It was very nics experience with you and im sure ill comback:)