Evidence that Supports my Current Theory

I think the Woodbridge Costco gas pumps shut off earlier than the ones
at the Fredericksburg Costco, but they both dispense accurate amounts of
gasoline.

I am happy when I go about 150 miles on the first 1/4 tank, according to
the fuel gauge. Last time after I filled up at the Woodbridge Costco, I
went much less than 150 miles, and this time is the same, I had gone
only about 130 as the needle passed down over the 3/4 mark.

The tank between, filled at Fredericksburg, indicated well over 150
miles as the needle dropped down the same mark.

The pattern forming indicates my fuel economy should be maybe 37 if I am
lucky when I fill up again at Fredericksburg. I will do my best to see
if I can refuel at the Woodbridge Costco to see if fuel economy matches
or is similar to fuel economy when I refilled consistently at the
Fredericksburg Costco.

Overall, however, I think average fuel economy numbers should not be
affected by this apparent problem, as it should smooth itself out over
time.