I have a question. When we picked up the car, we charged more than 50. I didn't understand what this money was for. Was it a deposit for the last box of oil, or did it mean that we didn't have to return the full amount we borrowed? Have any of you encountered this situation ?

Check the bill.

Refuel the car when returning it, and let him refund

When returning the car, there are three options. One is to return it according to the original fuel level, usually full to full, and it doesn't matter whether to show the refueling receipt; the second is to return the car with less fuel, and the rental company will send someone to refuel, so the charge is about three times more expensive, about 3 euros per liter; The third option provided by the car rental company is to charge 1 euro per liter for a full box of fuel, which is about 50 euros as you said. It depends on whether you feel rushed for time when returning the car. If you have time to refuel, don't choose the third option, but if you choose the third option, it seems that there is no refund. I have experienced both the first and second options, so this time I thought I was in a hurry and might not have time to refuel at the airport when I come back, so I chose the third option directly, returning the car with half a tank of fuel, and I don't know if I will get a refund.

We are like you in Munich. Forgot to fill up the car when returning it. After telling the waiter, she said it was okay, there was money in your deposit.