So what i did was take the 36 gallons, calculate the mileage vs tank size and came up with 15.2 MPG. Now i am in alabama and a wrestling coach so maybe i am sucking with a calculator lol...i did ask siri to do the math also and she agreed with meI live in a country setting speed limit 55. A mix of Highway 65 mph and country roads I just returned to the house 18.1 on dash. I always hand calculate at fill ups and find a 6 tenths difference less than truck shows. Yeah I drive like a little old lady easy on the pedal.