Hello, Jay. I was wondering the same thing about the first entry.
I took delivery of a 2016 Subaru Outback 2.5i two weeks ago, with 168 miles on the odometer. The dealer sends you off with a full tank of gas, so I put in a complete SWAG for my first entry. 168 on the odometer, EPA rated 25mpg city, must have been 6.72 gallons :-) I telecommute for work, so I don't drive too much, and haven't hit my first fill up yet.
I have been tracking my fuel consumption on my cars since I got a car in 1973. This is what I started out with Ward's Ever-Ready Motor Record Book/ My dad & grandfather both kept these.
I moved to a spreadsheet a long time ago, and I'm probably going to keep that going until I'm comfortable with Fuelly.