Thanks for all the great answers! They give me flexibility and multiple choices. I'm copying and pasting a list into my iphone for when we are there.
We haven't flown into MCO in a couple of years (we drive now from MA) but there is a Shell station really close to the airport that has exhorbitant prices! Skip them and drive a little bit down the road and there is (was) another gas station with better prices. Again this is information from a couple of years back so I don't know if it still applies.
We drove down starting Christmas Eve at 11 pm last December and all Christmas Day. Made it to Savannah by 5 pm.
We loved it! Family all together in the car, opening presents as we reached various states. However, my parents took me with them on vacation and I garnered Jetblue Wallet Money and points enough to fly down and half of the way back.
And yes, very first vacation I ended up at that Shell

It's so easy to do when you're in a hurry to get to the airport.
In the past we have used the Hess station by the Boardwalk and would fill up just before leaving. For the past several trips we use the Hess Station just before getting onto 417. They usually are reasonable pricewise and are the easiest to get to on the way to the airport - if you are using the 417 route. We use
Budget most of the time and have never had any problem filling at either place and returning the car.
There is a Wawa on 436...just outside the airport...great prices
Wawa, RaceTrac, Love's. Those are unfamiliar gas station names to a Northener! I was hesitant to use those wondering if they were scammy. Although, if the car is not mine.....

Just wouldn't want to cause trouble for the next family who uses it.
Thanks for the Wawa suggestion.
We will either fill up at Costco on OBT (10 mins from MCO) or the RaceTrac on McCoy, (5 mins from MCO).
Costco
2101 Waterbridge Blvd
Orlando, FL 32837
RaceTrac
1875 McCoy Rd
Belle Isle, FL 32809
Open 24 hours
Definitely helpful as we are primarily cruising on the Fantasy but may do one night on WDW after. If we don't, I've got these gas stations to go to from the port.
I am a Costco member this year. Wasn't sure if I was going to renew in December but my car rentals for this trip are actually a Costco booking. Great deal! 2 one day, one ways from the airport to the port and back $67 and $52. Guess I'll have to renew though we don't have a gas station at the Costco I go to.

I see the Costco you mentioned is $3.24/gallon right now. You know what gas is on Cape Cod right now? $3.84/gallon!

Thanks so much.
I see you're a local. Davenport seems to becoming the new Kissimmee.
Thanks
We usually use Dollar Rental and always fill up at the Boardwalk Hess and never had a problem - until this past February!
The woman behind the rental counter made it a point to inform me that the car must be returned with a full tank and I would have to provide a receipt from a gas station that was within 10 miles of the airport! I told her that in all my years of coming to Disney I'd never heard of this policy and she said it's always been in effect and seemed surprised that nobody mentioned it to me.
Needless to say, before returning the car to MCO I filled up at the Boardwalk Hess and nobody bothered to ask for any gas receipt.
I guess we just ran into an overzealous employee...
Jim
That's my luck exactly!

I always get that employee whose a stickler for the rules! You can understand why I need this info. I read the fine print as much as I can!
Got this off the DIS a year or 2 ago and have been using this place since then. We usually rent from Dollar and their policy states that you have to have a reciept from a station within 10 miles of the airport. They have never asked me for a reciept, but with my luck, the one time I don't worry about it, they'll want one!
"From WDW, probably the easiest stop within the 10 mile ring of the airport is a CircleK on South Boggy Creek, where you exit 417 to go to the airport. When you exit 417 at the airport sign, turn South on Boggy Creek (away from the airport) and go past Lock Haven Baptist Church and the cow pastures for about 1.5 miles off the highway.. The Circle K is kind of out there by itself at the next crossroad. It is just over 7 miles from MCO, so if you top up there, you can drive straight back North up Boggy Creek and into the airport.. The only time there in normally traffic on that part of Boggy Creeek is at church service time."
I think I know which one you're talking about as I turned the wrong way once leaving the airport. It was a delayed flight and about 1 am. Trucks stop there to fill up. Kind of eerie and creepy like you're in no mans land and then wham, there's a gas station!