Most weeks, I can squeeze a tank of gas in my 96 Mazda 4X4 to last all week. I drive 19 miles each way, 5 days a week, plus any running I have to do. Average maybe 240 miles a week. I'll have some gas left over too, so I'm getting maybe 22 mpg. If I have to do house checks, I'll drive 120-150 miles or more in a day, with maybe a dozen or more stops mixed in, so that drains it pretty quick.
I'm a speed limit driver on highways, and faster than speed limit on back roads that I am familiar with. I could probably conserve a little by altering my driving style.
The Explorer has been tuned up recently, so it does OK as well all things considered. AE drives a similar distance each day, with a bigger tank than the Mazda, so I'd guess her mileage to be around 18 mpg. She does a lot more running than I do, mainly because the three of us make a tight fit in a pickup truck.
We combine trips to town when at all possible. Rarely do we go into town just for one thing.
Prices are about $2.84 in the sticks, $2.90 in town here.