when I was in the military, they taught that we should never go below half a tank
Hubby was in the army and then was a firefighter for 33 years. He is OCD about gas in the car. I will run it to the red line but anything close to 1/4 of a tank deserves a fill-up in his view.
Wife is emphatic about it after being caught low during an impending Florida hurricane, when all the gas stations shut down and bailed.
Years later a mechanic said that with these new cars, driving too often with a low tank left the internal gas pump exposed and not insulated by the gas, and tended to fail more often.
Between the two, I now top off when I get near a half tank.
My wife and I argue about this. We drive cars with very good mileage. She fills up almost every time she passes a Sams Club or Costco (ok, a little exaggeration there), while I wait until 1/4 tank or so is left. That’s still over 100 miles until empty. I don’t think it is efficient to fill up at 1/2 tank, unless you plan on driving on roads where there is no gas for hundreds of miles.