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7.3 mpg trip on new 2013's history

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Old Dec 4, 2013 | 04:06 PM
  #11  
pspens's Avatar
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Joined: Oct 2013
Posts: 86
From: Indianapolis, IN
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Originally Posted by shipo
Were I in your shoes, I would track and compare the miles divided by fuel versus the OBC for at least ten tanks of fuel to determine the standard error; two tanks and 22.5 gallons simply isn't a large enough sample size.

Edit:
I see that the tank size of your car is listed as 17.2 gallons; to minimize calculation error during your ten tank test, it would be best of you would drive the car all of the way to near empty before refilling.
Well, I will continue to monitor mileage until the numbers converge. Unfortunately, I'm cheap and the fuel prices vary a lot here (Indy) and I try to buy at the lower prices, so usually I'm putting gas in at around 1/2 tank. It shouldn't matter in the long run as the pump errors should cancel (if 1 tank is a gallon short, then the next fill-up will contain an extra gallon if the pump stops correctly.)
 
Old Dec 4, 2013 | 05:09 PM
  #12  
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Right. Just make it 10 or 20 CONSECUTIVE fillups. That way each fillup might be more or less full, but will be corrected by the next fillup. Over a number of fillups, you get much less error if they are consecutive fillups.

However, if you keep clicking the nozzle to top off the tank, you introduce another error. When you do that, you risk the vapor-recovery system sucking liquid fuel back into the hose. You pay for that fuel, it registers on the pump, and you count it in YOUR calculation of MPG. But it doesn't get in your fuel tank so the onboard computer doesn't include it. This error can get larger if you fill more often from 1/2 or 3/4 tank.

Driving on different size tires will affect your MPG overall. But you base your calculation on the odometer reading, and so does the onboard computer. So it's still a valid comparison.
 
Old Dec 4, 2013 | 08:31 PM
  #13  
pspens's Avatar
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From: Indianapolis, IN
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Originally Posted by JimBlake
Right. Just make it 10 or 20 CONSECUTIVE fillups. That way each fillup might be more or less full, but will be corrected by the next fillup. Over a number of fillups, you get much less error if they are consecutive fillups.

However, if you keep clicking the nozzle to top off the tank, you introduce another error. When you do that, you risk the vapor-recovery system sucking liquid fuel back into the hose. You pay for that fuel, it registers on the pump, and you count it in YOUR calculation of MPG. But it doesn't get in your fuel tank so the onboard computer doesn't include it. This error can get larger if you fill more often from 1/2 or 3/4 tank.
Right. It will be consecutive fillups and I don't click to top off. I put it on the slowest setting and when it stops, that's it.
 
Old Dec 5, 2013 | 01:14 AM
  #14  
UhOh's Avatar
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From: Washington State, USA
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Originally Posted by Jimbo12000
Just bought a new 2013 EX-L 4-cylinder three days ago, and noticed the next day that the earliest trip on the history display was one of 15.0 miles with only 7.3 mpg.
...

So, is this ... Evidence that I should get a life?

Thanks,
Jim
Yes. Enjoy your new car; and also get a life.
 
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