gnaget

I think you need to categorize it by convenience. For some airports it's a hassle so one should fill up within range, e.g. 50 miles when you pass a station. For example, many (most) people going DCA access it via the GW Parkway and getting to the gas stations on route 1 is a pain. You would have to go up onto the airport loop and then out over the bridge down to route 1 and then make a U-turn.

Other airports are convenient where I don't bother filling within range. E.g. IAD and IND. At IND there is a BP station maybe 200 meters away on the corner where you make a right turn down to Avis.

Even DTW is a nuisance since you have to turn left and then it's a pain to get back out across traffic. I fill in Warren and have no problems, which is 30+ miles away.

At BOS getting to that Citgo on the airport loop is a pain so I would always fill in advance. Don't even ask me how to get there with the new maze that they created.

ROC: there is a Sunoco just before the turnoff to the airport. That one's easy.

PIT. There is a gas station with specific signage as you enter the airport but it's really on the way out so you would have to loop back. Again, I always fill in advance at PIT for this reason.

DAY: There are none. The closest requires that you exit right onto route 40 before final stretch of access road. There is a Shell station in the charming town of Vandalia (sic) on your right a mile or two down the road. If you are coming from the north then it would be better to exit onto route 40 off I-75 rather than going down to I-70 and taking the acces road. But the best bet is to fill in advance.

NUE: none. Make sure that you fill up on the way. You will pass a zillion gas stations in either direction on the ring road.

CPH: there is a Statoil right there but you have to go slightly past the car rental return garage unless you are coming from the west.

ARN: there is a Statoil within the airport area but not convenient for car rental returns. I would stop at Eurostop an exit or so before if you are coming from Stockholm.

BRU: I never noticed any. I fill in advance. If you go the normal way from downtown via the tunnel there is a Total on LHS of the major one way street (forget the name) just before the tunnel. It's one of those urban inside the building jobs with one lane and two pumps.

LHR: The Texaco on Bath Rd, west of the Avis, maybe 500 m. On the LHS if coming from the west, so convenient since they drive on the left. I think the corner is Sipson Rd if you look at a map.

LAX: There are several gas stations in the area. No worries. You will pass one.

SLC: None. I go there frequently and always fill up in advance.