In the previous post, I laid out how we were going to be computing fuel economy in the 2007 Honda Civic GX now that we're using a home fueling unit that doesn't provide a way of measuring the amount of compressed natural gas being pumped.
After a lot of calculating, estimating and talking to Honda engineers, we decided to assign a value of .368 gallon-equivalent to each bar on the Civic GX's fuel gauge. Thus, if we were down 10 bars and refilled overnight, we'd figure we'd pumped 3.68 gallons.
To double check, I ran the tank down by 12 bars this morning and pulled into the neighborhood Clean Energy retail CNG pump to fill it back up on a pump that does measure gallonage...
At our assigned value of .038 gallon per bar, I expected to pump 4.416 gallons
The readout on the pump said we got 4.471 gallons when the tank registered full.
So our "best guesstimate" method of figuring fuel use was off by just fifty-five thousandths of a gallon (0.055 gallon, to be precise).
John O'Dell, Senior Editor, Green Car Advisor @14,192 miles
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