Moe DeLoughan wrote:

Back when I was a young 'un, I drove an old beater with an unreliable
gas gauge. I got in the habit of setting the trip odometer every time
I filled up and noting the miles I'd used on that tankful. I knew when
I'd put about 250 miles on, it was getting close to time to fill the
tank. It's now a habit. I never look at the gas gauge, I check my trip
odometer.

The gas guage causes me to look at the trip odometer. That decides if It's time
to get gas. The trip odometer is a way more accurate indicator of how much gas
is in the tank.