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Old 12-29-2009, 05:07 PM   #17 (permalink)
jamesqf
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Quote:
Originally Posted by MetroMPG View Post
I guess whether it's slow or not depends which gauge you're using . Tank average? Slow to change (unless you just filled & reset). Trip average? Depends on trip length. Instant? Not slow, by definition!
Bad definition :-) It's the SG's "instant" mpg display (or the gallons per hour variety). Compare it to the instant display of the Insight (and I suppose any other car that has one), and you'll see that its response is far from instant. A good example is when you're driving down a level road in conditionw where the Insight spends most of its time in lean burn mode, but drops out every couple of minutes to do the purge of the secondary catalyst. You'll feel it happening, and see the Insight's display drop from around 75-100 mpg to 50-60 mpg. The SG won't even notice. You can also be getting 75+ mpg per Insight display with 50 mpg showing on the SG. (The Insight figures are backed up by trip miles & fillups.)

The SG's a neat piece of work, but in my experience all the fuel consumption-related displays are more like wild guesses than actual measurements. IIRC, the SG makers even admit this: they don't measure fuel consumption directly, but infer it from other OBDII measurements.
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