Shell

If you are returning a rental car, this is the closest place. Mind you, they do charge about 20c /​gallon than the guys one exit prior, but if you want the last minute gasoline prior to entering no-man’s-land at the airport, this is the place. It is kind of tricky to get their from the airport entrance, but if you pass it, you can circle the terminal and hop out to it anyway. It’s about ½ mile from the car rental return

When I rent a car in a new City, I’m offered the following options: prepay, fill up the tank just before returning the vehicle, or getting hit with a larger per gallon charge if I don’t want to bother. I usually go for Option 2 and have gotten pretty good at finding a nearby gasoline station to a given Airport.
This Shell Station is right across the street to MSY and an easy drive back to the rental car center. The only trick is making the right move when given the choice between traveling inside or outside the Airport property. A wrong choice is easily corrected, as long as you can put up with a series of very slow stop lights. Make sure to respect those and your speed, as Kenner PD has a certain «reputation».
And the per gallon price? It’s a little expensive, but a lot more economical than the Rental Car price or what’s available back in California.