“Now here’s the really interesting added wrinkle to this SCAM: He indicated that he’s convinced that these crooks have not only jiggered the pump monetary calculation mechanism but HAVE ALSO TAMPERED WITH THE VOLUMETRIC MECHANISM, CAUSING THE CUSTOMER TO GET FEWER GALLONS THAN THE AMOUNT INDICATED ON THE PUMP!!”
i have heard that the time of day affects the volume recorded as pumped, as gasoline expands as it warms up. but how any surface temperature may affect the volume of gasoline flowing into the car from a buried tank, i cannot see? there is some sort of caveat on a small label on gas pumps which may speak to this apparent discrepancy, but i cannot recall the wording oft hand.
Fill in the morning. There are net/gross volumes for fuel. Taxes are generally calculated on the gross gallons (which is what the fuel would be measured at at 60 degrees F, and sea level), then the net is figured on actuals. The difference can be up to 100 gallons on a 10,000 gallon load. But it averages out over time, due to seasonal fluctuations. More net in winter than gross, more gross in summer than net.
Used to work in the field, and it's been more than 10 years since, but IIRC, that's how it worked.