Very impressed with gas mileage

Oh, here we go again with slant 6 mpg tales.
I’m not exaggerating or telling tales. 27.8 miles per gallon averaging 60-70 mph. I would have not believed it myself had I not documented it. I traveled 78 miles and used 2.8 gallons each direction. I was assuming I would get 16-18 mpg. That’s why I documented everything to settle my curiosity.