Very impressed with gas mileage

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.

Did you verify your speedometer reading was correct with GPS? If that was reading high it would have given false odometer readings as well. Also how did you measure fuel consumption?