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  #1  
Old 04-29-2016, 02:59 PM
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Mpg drop while at idle

I was sitting in my car applying the uconnect update. It took about 20 minutes and in that time my mpg on the dash dropped from 14.7 to 13.5.

It's a V6 4x2 and I know 14mpg is low. But I'm associating that with my driving style since I respond to fires in my personal vehicle. My question is should I be concerned with that significant of a drop just sitting at idle?

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  #2  
Old 04-29-2016, 03:41 PM
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Re: Mpg drop while at idle

14mpg is super low... I get better than that with my 2012 V8 with oversized tires and the 6 speed transmission. But for your original question.. it seems a little excessive but not out of the question. If you're just idling, and not going anywhere, then it is bound to drop your avg MPG since you're going 0 miles but still using gas. Maybe someone else has a more scientific approach but it makes sense in my mind.
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Old 04-29-2016, 03:46 PM
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Re: Mpg drop while at idle

No you shouldn't be concerned. Why wouldn't the mpg drop? You are burning gas while not moving so it only makes sense that your average will decline during that period. Just putting your ignition on would have been fine, there's no reason to have the engine running while you do updates.
14mpg is low, but this all depends on driving habits and where you drive. A car can be advertised at 19mpg combined, but if you are stopped at lights and/or accelerating 80% of the time then of course it's going to be low. If you had the V8 in your car it would be even lower.
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Old 04-29-2016, 03:57 PM
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Re: Mpg drop while at idle

Also, (assuming you reset your mpg at fill-up) if your tank was mostly full, it wouldn't have many miles for the average, so it will drop fast when idling. If you're at the end of your tank, it probably won't drop much at all, even if you sit for 1/2 hour.
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Old 04-29-2016, 04:03 PM
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Re: Mpg drop while at idle

^^ that's also true. put it this way.... A vehicle gets 0.0mpg idling, our Jeeps get maybe 5mpg accelerating. Do that for most of your tank and it's not possible to get good fuel economy or even close to the advertised mpg figures regardless of what engine you have.
But what DriveDave said is correct, the more recently your mpg page was reset, the more sensitive it is and the more drastic it changes.
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Old 04-29-2016, 04:51 PM
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Re: Mpg drop while at idle

Miles per gallon... you are not driving any miles so of course the avg. is going to drop.
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Old 04-29-2016, 05:57 PM
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Thumbs up Re: Mpg drop while at idle

Obviously if you're not going anywhere and burning gas your mpg average will go down.

14mpg average seems a bit rough though. Granted, if you're idling a lot / revving the tits off it when you do get moving, it's entirely possible even with the little engine.
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Old 04-29-2016, 09:28 PM
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Re: Mpg drop while at idle

idling just tosses 0's into the calculations along with outside temp etc
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Old 04-29-2016, 10:44 PM
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Re: Mpg drop while at idle

You ever ask a question only later to realize how dumb it truly was?

Of course MILES per gallon will drop when going 0 miles. The rate at which it was dropping tossed my common sense out the window!
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Old 05-03-2016, 02:43 PM
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Re: Mpg drop while at idle

What's even more amazing is that your l/100 km will go up when you are idling! Maybe that'll be comforting?
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Old 05-03-2016, 04:11 PM
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Re: Mpg drop while at idle

I really feel we need to pass this information onto the fueleconomy.gov websites administrators. We need them to add an additional column to city and highway mpg. This third column will be called "Not Moving MPG"

I am actually pretty worried now about this as i have not looked into the 2017 specs on MPG while not moving
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Old 05-03-2016, 07:28 PM
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Re: Mpg drop while at idle

Theoretically.... ...MPG while idling stationary is...zero. Lots of gallons, but no miles. LOL
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