I've said it before and I'll say it again.
Don't rely on the gas gauge.

Do the math instead.

Use your trip meter to log the miles traveled from your last fillup.
Divide those miles by the actual amount of gas purchased.
You'll get better results than you think.

By the time my needle nears the half-way point on the scale, I have about 100-110 miles on the trip meter. But by the time I get down near empty, I've only burned 8 or 9 gallons out of more than 13 gallons total capacity. The gas gauge is horribly inaccurate.

Long story short, I'm getting the same feedback as you are... but the math calculates out to 26 miles per gallon.

You're getting better mileage than you think.