We are taking a trip from Wisconsin to Nevada then back to Wisconsin. How low should i let our fuel tank get?

i really don’t know about the saving money part, but if you are taking a long trip and putting a good strain on your car never let your gas run all the way down. your gas actually helps to cool your fuel pump and if it gets to low it will heat up and burn out, very common on GM vehicles, resulting in about a waste of time and fat repair bill.

Agree with “Micheal” don’t let it get below 1/4 tank.

To get a safer reading of how low the fuel tank is than using the gas level gauge, reset your trip odometer to zero miles at each gas station fill up. Then if your car gets 25 miles per gallon and the trip odometer reads 250 miles driven, you’ll know you’ve used up about 10 gallons of gas from when the tank was full. I would not let the tank get below 1/4 full for many reasons including the first answer above.

the level in the tank has nothing to do with fuel economy. as long as you fill the tank when it gets close to empty you will be fine. the weight of the vehicle is about the only variable in your control.

Depends. Gas has weight. 1 gallon is about 10 lbs. So if you have a 20 gallon tank you are carrying 200lbs(or a couple of extra people). On every hill going up you are gonna have to give it more gas to carry that extra 200 pounds up the hill. So, weight matters.
Whereas “Chuck-the driver in the exact same vehicle as you” has 1 skinny person as a passenger (in other words a partially filled gas tank and it is half empty. So he scoots up the same hill without even touching the accelerator(basically using near to nothing in fuel) because he is hauling maybe 60 pounds up the hill(in stationary fuel weight)..
This also applies to every stop sign or light that you come to and have to stop completely.

Grade 5 math.