I canceled my Costco membership earlier in the week, and my Costco
American Express card still worked.
However, my data tracking spreadsheet is not working, so all I can say
is that my last tank provided me with 418.5 miles. I put in 10.532
gallons, making for a fuel economy of 39.74 miles per gallon.
As you know, I had put in one ounce of acetone this tank. I refueled at
the Woodbridge Costco, which I suspect has the automatic shutoff feature
set at a higher sensitivity setting, so that less fuel is put in the
tank than otherwise ought to go in, which artificially inflates my fuel
economy numbers. I did not bring the acetone bottle with me, so I could
not add two ounces for this new tank.
In short, my higher fuel economy on this last tank may be due to the
fact I refueled at the Woodbridge Costco just as much as it may be due
to the acetone I placed in the last tank.
I am totally excited that my I was still able to get Costco gasoline, as
it was three cents per gallon cheaper than a nearby gas station. But I
will still start looking for gas stations that serve 100% gas rather
than the gas/ethanol blend that Costco delivers (10% ethanol per the
pump sticker this morning).
A few days worth of in-town driving were done on this tank, so the
increased fuel economy was a moderate surprise. If my next tank shows a
big dip in mileage, say down to 36 mpg, then my idea that the Woodbridge
Costco gas pumps are more sensitive will stand. If it's higher, like
37.5 ot 38, then perhaps the acetone theory has some merit.