Truck has a 36 gallon fuel tank, I've done over 600 miles on a tank and passed many gas stations on road trips. I think they hit the nail on the head, perceived savings at the pump doesn't equate to actual savings once you buy the car and pay for increased insurance etc. It is the feeling of "saving" by getting better gas mileage in the moment. When I drive my truck to work I'm not thinking how I enjoy driving the truck, instead I'm thinking about the fuel I'm burning instead of running my pontiac. I'm a fill the tank full every time I'm at the pump kind of guy, also calc my mpg for that tank every time. This probably doesn't help my thinking but is good to notice things like low tires pressure, dirt air filter, brakes dragging but not causing heat issues. I've found things like that from noticing dips in mpg.
It's a frame of mind I need to work on.
Sake of transparency, my 5.0 F150 is level/lifted with 6100s sitting on 34s and has 4.56 gears. Took it on a road trip before getting the expedition and returned 16.5mpg calc'd PA to OBX and back. Does about 14 locally unloaded with shorter drives and all our hills.