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Averaged 42 mpgis this even possible?


10162009, 08:03 AM  #23 
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What's the topography of that route? Is it constant elevation, downhill, how steep are the hills?
65 miles is not far. If a there is a significant downhill grade during that route your final average will reflect the benefit from the downhill stretch. If there are no appreciable uphill segments then I could believe that reported average. For a fair test you could have immediately turned around and driven back the reverse route...that would negate the benefit from changes in elevation and to some extent tail wind. 
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10162009, 10:12 AM  #24 
just another bmw douche bag
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as much as I like to see my mileage meter sweep up into the 50mpg range, I realized you need to do the math at each fill up to calculate the true mileage. All the variables eventually average themselves out by the time you empty the tank.

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10162009, 10:52 AM  #26  
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Quote:
Relying solely on the display is like predicting the weather using the outside temp gauge. 

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10162009, 11:21 AM  #27  
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Drives: 2006 330xi 6MT Join Date: Aug 2009
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Quote:


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10162009, 01:12 PM  #28 
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Drives: 2006 330xi 6MT Join Date: Aug 2009
Location: Santa Clara, CA

Out of curiosity, do you have an estimate on how much you save per year with all those calculations?

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10162009, 01:20 PM  #29 
Smiling politely
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^^ Takashi  I do the same, albeit for informational kicks only, not trying to save $$. My car is a DD, so I generally always go to the same Shell gas station near where I work, even the same pump. Looking back on the data, the best tank I've had is 27.9 mpg actual (computer reported 28.0 for that tank), back in June 2007. Basically all highway for that tank, but driving through the Shenandoahs, so quite hilly.
I discussed this in another thread, but the computer is inaccurate. In 144 tanks of gas, it's never gotten the mileage exactly right. In fact, it has always reported too high. On average, it reports about 0.4 to 0.5 mpg too high, but it has been off by 1.0 mpg or more several times. Also, the computer rounds calculations in l/100 km, then converts to mpg, so you see strange rounding issues when you consolidate the data. Try sorting your "computer mpg" column on your spreadsheet and see how the numbers increase by 0.2 or 0.3 consistently, and the computer never reports the inbetween numbers. Also, the gaps in reporting intervals grow as you get to higher mpg numbers, since it's rounding at vol/dist and then converting to dist/vol. It is inaccurate over and above that rounding error, though. Anyway, this is uninteresting to most, but I thought maybe you, as a fellow gas tracker, might be interested.
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10162009, 10:27 PM  #31 
Drive till Infinity
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Drives: Jet Black '07 328i (E90) Join Date: Jun 2009
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So I guess I DID not average 42mpg. I probably should have stated where I got this reading anywaymy GPS system.
As for where I was travelling, it was on the LIE (I495) traveling east bound from Jamaica to exit 62that is, if anyone is familiar with that area. As for the terrain, I'm not sure if the whole way is mostly downhill, or uphill or even just straight. I guess I'll be keeping an eye on it next time I travel. It was nice to think that I had 42 though =(
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