To Goose's initial question, there are several gas stations in close proximity to the Hertz location at LAX - at least two within a few hundred meters. (I wish I could remember street names or freeway exits, but I recall I gassed up my Hertz car no more than 2 minutes of driving from the rental return lot.)

I would definitely not attempt to FPO at LAX. Last thing I'd want to do is get stuck in an all-too-common LA traffic jam as I'm trying to roll a rental car into LAX on fumes.

I used to use FPO when they had the big V8 Mercury Cougars in the mid-90's. I owned one myself and knew the engine and gas tank very well. I haven't done it in years though...