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12-08-2009, 04:55 PM | #1 |
Drives: 2008 Yaris Liftback (Sprocket) Join Date: Oct 2008
Location: San Antonio, Texas!
Posts: 2,799
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Winter Gas Causing Drop in MPG?
Here's the situation...since getting my 5K service back on 16 May, I've been getting between 36-38 MPG in my 08 auto hatch with Rike Raptor 215/45Z17 tires on it. But I got gas on 11 October and only got 34.6 MPG on that tank. I've been driving the Jeep a lot lately, so I didn't fill up again until two days ago; but this time I got even worse gas mileage...33.4 MPG.
Last year (I bought the car in Oct 08) I was only getting 32-34 MPG until I filled up in February, when it went up to 34-35 which it stayed at until I hit 5,000 miles and had the first service completed (with synthetic oil). Now I know most of the gas around here now contain up to 10% ethanol, and that we might be getting "winter gas," which has lighter, low-boiling-point components are added to it to increase volatility, which may improve emissions and have a relatively high octane blending value but also is more expensive and lowers fuel economy. Allegedly, "the oxygen-bearing compounds displace fuel components, so it takes more fuel to get the job done. Normal gasoline has a stoichiometric ratio of 14.7:1, reformulated winter fuel runs between 14.3 and 14.4:1" (Source). Now the kicker, it seems like my Jeep is getting better gas mileage! Lately I've been averaging well over 16 MPG, as compared to 13-15 during the summer. Some of that may be due to the fact that it is "buttoned up" (top and doors back on), which believe it or not makes it more aerodynamic versus with everything off. My driving habits don't seem to have changed, and since we don't really get winter weather down here in southcentral Texas (other than more rain), I can only attribute it to possibly being that the old I6 4.0L engine in my Jeep likes winter gas better than the I4 1.5L in my Yaris. Does that make any sense? I am open to any other theories or observations... Cheers! M2 |
12-08-2009, 05:04 PM | #2 |
DWEED
Drives: 3DR 2008 Metorite Metalic Join Date: Oct 2008
Location: Arizona
Posts: 1,161
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I experience a loss with out winter fuel blends. About 2 mpg. Some of the milage loss might be due to longer warm-up times and driving on snow packed, ice packed, or wet roads.
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Making a decision without following it with an action is still a fantasy. |
12-08-2009, 06:34 PM | #3 |
Steals terrorist's lunch
Drives: 2007 Yaris Liftback Join Date: Mar 2007
Location: Reno, Nevada, USA
Posts: 1,299
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I have never heard of any type of vehicle doing better on winter RFG, so I bet it is mostly due to both enclosing the cabin space, as you suggested, and the slower speeds on the roads during inclement weather. For hill climbing too slow a speed hurts fuel economy, but in the flat lands of south Texas it rocks.
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- Brian Share the Road I often carry 2 carpool passengers and mountain bikes or snowboards/skis over a 4,500 foot elevation difference. Click the graphic above to see my detailed mileage logs. |
12-08-2009, 06:49 PM | #4 |
Half a Bubble Off Plumb
Drives: 2009 Yaris Sedan Join Date: Mar 2009
Location: Bristol, Tennessee, USA
Posts: 1,593
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Under recent market conditions, the volatile butane and pentane components added to increase volatility of winter gas are a lot cheaper at the refinery level than the heavier gasoline hydrocarbons. That's one reason gas prices tend to be lower in winter and higher in summer, when they can't use the butanes. Butanes can be run through a process called alkylation to make iso-octanes, which are high octane fuel components, but the processing adds to the cost.
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12-09-2009, 06:39 PM | #5 |
Drives: '09 Yaris Sedan Join Date: Oct 2009
Location: Western N.Y.
Posts: 75
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Here in western New York we got screwed a few years back with the winter blend. Oxygenated fuel. Read Ethanol. Now we get screwed year 'round. Every pump in the area has a 10% ethanol sticker on it. Ethanol starts to evaporate when it hits the air. You get to pump more. The evap systems on the cars today can't hold the alcohol fumes. You get to pump more. Alcohol does not have as much energy content as gasoline. You get to pump more.
Who is the winner in this mess? doc |
12-09-2009, 07:01 PM | #6 |
Steals terrorist's lunch
Drives: 2007 Yaris Liftback Join Date: Mar 2007
Location: Reno, Nevada, USA
Posts: 1,299
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Corn farmers (who get heavy Federal subsidies to grow the corn the ethanol is made from), Monsanto (who makes the genetically modified corn seeds the farmers buy from them each year), and the oil companies (whose drilling efforts produce the raw materials for the synthetic fertilizers and pesticides used to grow the corn).
Pretty much everybody else gets shafted.
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- Brian Share the Road I often carry 2 carpool passengers and mountain bikes or snowboards/skis over a 4,500 foot elevation difference. Click the graphic above to see my detailed mileage logs. |
12-09-2009, 10:33 PM | #7 |
Half a Bubble Off Plumb
Drives: 2009 Yaris Sedan Join Date: Mar 2009
Location: Bristol, Tennessee, USA
Posts: 1,593
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Yeah, IMO it's foolish to grow food and ferment it to fuel. I've really got no problem with the alcohol in the fuel itself. Most of the purported problems have been exaggerated. I believe our Yarises would be fine if there were 25% ethanol in the gas as they run in Brazil, but we need to develop better sources than corn for biofuels. It's far too inefficient, and has run up food prices.
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12-09-2009, 11:55 PM | #8 |
Drives: 08 Yaris sedan auto / Fit auto Join Date: Oct 2009
Location: northeast
Posts: 2,897
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yup , between ethanol , winter blend , colder weather ( longer idling to defrost windows ) , studded snows , and rain / snow / ice covered roads the mileage has dropped 4 > 6 m.pg. for both YARIS .
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12-13-2009, 01:29 PM | #9 |
Drives: Red Yaris Liftback Join Date: Mar 2009
Location: Where Only Yaris' Can Go
Posts: 71
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Mine has dropped a bit too, but I thought that it was due to a SRI that I had put on recently. Maybe the drop is due to both.
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12-13-2009, 05:18 PM | #10 | |
Drives: '09 Yaris carmine red 2d HB Join Date: Jun 2009
Location: Middletown, NY
Posts: 1,502
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Quote:
The ethenol actually burns cleaner than gas and the cold air enables more oxegen in the fuel mixture. However, as you (and others) have pointed out cooler air means longer idiling times and this alone can make a differece in MPG. |
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12-13-2009, 05:34 PM | #11 |
Half a Bubble Off Plumb
Drives: 2009 Yaris Sedan Join Date: Mar 2009
Location: Bristol, Tennessee, USA
Posts: 1,593
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I often have to put on my defroster and then realize much later I've still got it on when it's no longer needed. The defroster runs the air conditioning compressor, so it eats gas.
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12-14-2009, 11:44 AM | #12 |
Drives: '07 Yaris HB Join Date: Apr 2006
Location: Sudbury, Canada
Posts: 520
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Most of the gas places up here have 15% Ethanol all year round ... so I always get not-so-good mileage.
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12-14-2009, 03:11 PM | #13 | |
Reluctantly Crouched...
Drives: 2008 Yaris HB M/T Join Date: Oct 2008
Location: DFW, TX
Posts: 867
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Quote:
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12-14-2009, 05:25 PM | #14 |
Drives: 2008 Yaris Liftback (Sprocket) Join Date: Oct 2008
Location: San Antonio, Texas!
Posts: 2,799
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That's odd, 'cause I am south of you in San Antonio and although our weather has been cooler and damper; I've only noticed a decrease in gas mileage!
And YH, I don't usually run my defrosters (windshield or back window) for more than a minute or two. I never leave them on for any length of time... |
12-14-2009, 06:36 PM | #15 |
Half a Bubble Off Plumb
Drives: 2009 Yaris Sedan Join Date: Mar 2009
Location: Bristol, Tennessee, USA
Posts: 1,593
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I don't run the back one often or for long, but the windshield usually just fogs right back up when I turn the defrost off, once it's started doing that. I try to run it in "pulses," but sometimes I just leave it on and then I may forget it.
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12-14-2009, 06:45 PM | #16 |
I love momentum.
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My MPG almost always drops in winter. So far I'm seeing 2mpg less than summer.
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12-14-2009, 09:12 PM | #17 |
Drives: 2008 Sedan White Join Date: Oct 2008
Location: Ohio
Posts: 54
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Don't feel too bad, I was doing 45 46 in the summer. Winter fuel dropped it down to 40 41. Then I put my studded tires on and last two times at the pump I'm at 37 and 38. Mostly driving the same. Good grip in the snow and ice tho.
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12-15-2009, 12:28 PM | #18 |
Reluctantly Crouched...
Drives: 2008 Yaris HB M/T Join Date: Oct 2008
Location: DFW, TX
Posts: 867
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Must be some other factor. Nothing about winter fuel should improve mileage, and every other car I've owned suffers on winter fuel. I know Dallas is an EPA zone that gets "cleaner" buring gas, so maybe the winter version is "normal."
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