Ruger
FRF Addict
Corrected the date info.The time periods you referred to for the two mileage calculations are the same. From May to March is a long time to use for a reference due to possible errors in gallons bought and remembering exact driving conditions. .7 seems to be within the margin of error to me.
I write down mileage and gallons and calculate MPG at each fill up. No memory work involved, so no memory errors possible.
All of that was general around town driving and one or two cross-state Interstate trips.