You need to return your vehicle with a full tank. The right time for choosing a place where you can do it right after you take the car. While driving from the airport or our rent a car agency, make notes about local petrol stations and plan to return to the end of your lease at the end of your lease to the one that is easiest to arrive or the cheapest. The approaches to the airports can be confusing and unknown to you, especially in Belgrade, because you go to the highway by yourself, so you do not want to go round the circles or follow the signs for the next exit from the highway in search of a gas station and the flight time is approaching. Plan everything in time, while you still have it.