In a previous and now closed thread from 2019, Roberto recommended a last stop to fill up before returning your rental to FCO. The stop is a Q8 on the GRA. We went there yesterday only to find the benzine side closed (and it looked like it had been for some time). At that point, it seemed too much of a hassle to get off the autostrada and find a station on street level. We turned the car in short 1/2 tank and ended up paying 2.47 euro per liter inclusive of the refueling charge. If I had it to do over, I would have filled up at another station about five minutes earlier.
It was open on July 15, 2024. However I don’t think it was a Q8. I think it was Esso or IP. It is strange a gas station at an area di servizio would be closed, but maybe they are working on it now.
When you fill the car in Italy and the gas attendant does it for you, make sure you are charged the amount they actually pumped in your car. So keep an eye on the amount the pump shows and the amount they charge you. Make sure the two match. There are a lot of dishonest people in Italy who take advantage of tourists, especially foreign tourists, and gas attendants are not much better than taxi drivers.