Friday, August 10, 2007

Data Collection Galore!

I recently added two more pieces of data to my fuel economy collection
process: outside temperature at time of fill-up, and miles driven before
the low fuel light comes on and stays on.

Right now, it may bee a bit too much to track the times that low fuel
light comes on, goes off, comes on again and stays on. But perhaps in
the future I will become more retentive and start tracking that as well.

My starting to track temperature is a direct response to the several
reports I have heard about the consequences of "hot gas." The radio, TV
and newspapers have each reported this summer that gas is metered to
flow one gallon at 70 degrees (or thereabouts).

Allegedly, gas expands when it gets hotter, so during hot days the one
gallon you pump will enter your gas tank and presumably shrink as it
becomes cooler in your gas tank.

Also, hot expanded gasoline allegedly provides less power and therefore
worse fuel economy.

Immediately, I wonder if my gas tank is cooler than the storage tanks at
the gas station. I think not, as the storage tanks are usually
underground. My basement's underground and is consistently nice and
cool, even on hot days. If this holds true for underground gas tanks,
then much of the "hot gas" story evaporates.

There may be truth to the story that extra gasoline hangs out in the
hose after you pump it. If that's true, then that gas conceivably could
expand and victimize you. Solution: buy gas on a hot day right after
someone else at the same pump, so the gas in the hose doesn't have a
chance to heat up.

Regardless, two recent tanks of gas have been pumped at hot
temperatures, well over 90 degrees. My fuel economy did not appear to
be harmed in any way.

I wonder if news reporters experimented to see if this was true before
they reported it, or if it's just one of those stories that comes over
the wire on slow news days.

From my experience and hard data, "hot gas" is not a problem to be
concerned about. This is why I will continue to track outside
temperature at the time of my refueling, to see if any major variances
occur due to extreme heat. Or cold, for that matter.

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