It is also a known fact that from the 1950s to the 1980s, maybe later too, car companies engineered fuel gauges to stay longer at the top of the gauge, with the intent being to give new car buyers a "warm fuzzy" about how great their new car was doing on gas mileage, so they could pass on word of mouth to their friends. That's true.

It is ABSOLUTELY NOT TRUE that you actually get better mileage when the tank is fuller.

My ex-wife and I had this argument once and she lost. She had actually thought that since the needle "barely moves" for the first 100 miles or so, then you can get better mileage by keeping the tank topped off !! Her Dad said so !! (long sigh)

Blondes, what can you say?