300 miles on a full tank of gas

FERRARI

Sorry if this sounds like a know-it-all....but The way that I have always measured MPG is easy......I fill up and force-fill.......the tank.....dont worry about doing this, I have been doing it for decades and never had a problem with any car. By force-filling I mean: After you think your tank is full, I shake the car and let the gas level go down. Any car will hold and extra 2 to 3 gallons..........it may take about 5 minutes to get all the air out of the tank. By doing this, you get an accurate level to refill the tank on the next fill.
Record the miles till the next fill.........and then you have an accurate level to measure from...........the next time you force-fill your are going to know that the level is the same as before.....as in FULL

Say you go 350 miles and then force-fill again.....it takes 13 gallons.....since you know the tank has been FULL to the same point...you know that you have used 13 gallons....and your MPG was 26.92 MPG

To me this is the most accurate way to get an MPG for a car........I guess I am Squirrly but I do this almost every tank....