I live here but recently I was reminded of the things that can happen to tourists. I'll make it brief. The advice is, if you rent a car, don't fill up the tank on the way to the airport when you are going to return the car; instead, fill up in town. I was leaving on a trip and my route took me towards and past the airport entrance. Just before the entrance I stopped to fill up. The routine did not seem normal, to me. One attendant put the nozzle in the filler pipe and summoned another, who turned out to be English speaking. No one "zeroed" the meter, which was already a departure from the norm here. I insisted, and they did. Then, the attendant engaged me in a distracting series of questions- if I was returning a rental car (I wasn't), was I "on vacation" and for how long, where I was headed, etc. Although my wariness alert was on I was anxious to get away from the harassment and left 100 pesos in change behind- so they won, in the end. In town I'm not subjected to this and recommend to any tourist to fill up in town, not on the highway to the airport, if you have an alternative.