You only have to refuel if the tank is less than a quarter full when you return it. In this case, you pay cashless with one of the fuel cards that is in the on-board wallet. You can find the tank PIN as soon as you have started the journey in the app under 'Help?'. Please note that the fuel cards are only valid at selected gas stations: Overview of gas stations. 

Fuel card misuse is always reported. If you ever have to pay in cash, please send a scan of the receipt including the completed “cash payment receipt”, which you can find in the on-board folder, to info.railanddrive@oebb.at. The amount paid will then be refunded to your account. If you don’t find the fuel card in your vehicle, contact the ÖBB Rail&Drive hotline: +43 5 1778 7333.