Winter Gas Causing Drop in MPG?

[MadMax]

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 (http://zhome.com/ZCMnL/PICS/winterGas/winterGas.html)).

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

[nemelek]

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.

[BailOut]

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.

[Yaris Hilton]

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.

[docB]

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

[BailOut]

Who is the winner in this mess?
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.

[Yaris Hilton]

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.

[Hershey]

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 . :frown:

[Mistry]

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.

[RedRide]

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 . :frown:

Agreed.

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.

[Yaris Hilton]

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.

[devinlamothe]

Most of the gas places up here have 15% Ethanol all year round ... so I always get not-so-good mileage.

[ozmdd]

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).



Does that make any sense? I am open to any other theories or observations...

Cheers! M2

My mileage has also increased by 2-3 mpg recently here in Dallas, with no discernable change in driving habits or changes to the vehicle. The weather has been much cooler with low humidity, and I have my foglight opening slottd to draw in dense, cool outside air, which has been REALLY cool lately. I had planned to cover the opening for winter, but the mileage has me curious. I think we may actually have an engine that likes the winter blend gas, or maybe its a combination of air density and the gas, or just the air.

[MadMax]

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...

[Yaris Hilton]

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.

[schleppy]

My MPG almost always drops in winter. So far I'm seeing 2mpg less than summer.

[minicorolla]

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.

[ozmdd]

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."

[daf62757]

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.

Sugar cane and sugar beets are far more superior to corn. The corn farmers just have a better strangle hold on our corrupt government.

[mdesjarlais]

you guys ever think that the long term fuel trim is boosted up a point or two due to the extra amounts of oxygen being sucked in by the dense winter air? i would hope you get worse mileage, otherwise that bad boy is runnin' lean! also factor in the defroster running almost daily. I get horrible mileage with mine compared to what i should be getting. I also have a slightly heavy foot...

[Hershey]

got to figure in taking longer to reach operating temperature during cold than those warmer days . Thus using more gas with higher idle .

[TheSilkySmooth]

I was just going to make a thread on this! My last fuel mileage calc with rotella diesel 10w-30 motor oil in the sump was 33.6mpg. Then I just changed over to 3 qts M1 AFE 0w-30 and the rest M1 5w-20. The car now has a real noisy cold start and run for 15mins. I just refilled the tank a 1/2 hour ago and I got 32.4! I dont like this synthetic oil! I was getting 38mpg last winter running PYB 5w-30 dino. I wonder, too, if the exhaust is getting plugged? There is a TSB on this for the 3 door for the exhaust plugging and a free replacemnt exhaust system if you have fumes (sulphur odour) in the car.

[vten]

i don't know if it's the gas or else , but my yaris mpg is pretty bad during the winter time ....26mpg :eek:

I believe partly because of the remote start engine that running around 10 minutes each time , twice a day ....and Im still using the same tires setup + full header back exhaust ....

:iono: oh well Im driving less than 10 miles everyday to work anyway :tongue:

[Yaris Hilton]

It's the remote start. I hate to let a car idle to warm up, though I've done it to defrost windows. All the fuel that's burned at idle is wasted, it increases noxious exhaust emissions, and that's when the engine really builds up sludgy glop in the oil from condensed moisture and partly burned fuel. In the old days it'd often cause cars to trail blue smoke from gummy oil making the piston rings stick in their grooves. Still might, but newer oils suspend sludge better. Much better to drive away and let the engine warm up more quickly.

[Black Yaris]

i am very surprised no one has pointed out the fact

stock tires:
Circumference: 74.58 in 1894.3 mm
Revs per Mile: 876.1

your oversized tires:
Circumference: 77.31 in 1963.6 mm
Revs per Mile: 845.1

so that means every 100 miles your car thinks you drive, you actually drive 96.5miles

so you are getting worse mileage than you think

[MadMax]

Yo! YarisHilton, what happened to your beard?!? :iono:

And Black Yaris, I have checked my speedo against my GPS, and it is accurate. I wondered about this when I initially got the car because I have 17" wheels on it; but either the dealership calibrated the speedo or the larger tires reduced the speedo error (which happened on my Jeep when I went from 29" tires to 31" ones.

And since I've had my Yaris for over a year old, that could not be a factor in the decreased mileage.

Cheers! M2

[YarisOwnersDad]

Oversize tires will cause the odometer to register fewer miles than actually driven, not more miles. So, you would be getting better mileage than you think, not worse.

Think of it as the car traveling further for each rotation of the bigger tire because of its greater circumference.

By the way, who was the roundest knight at the Round Table?






























Sir Cumference, of course!

[Yaris Hilton]

By the way, who was the roundest knight at the Round Table?

Sir Cumference, of course!

I resemble that!

Time to look like Santa's over till next year. :biggrin:

[MadMax]

Thanks YarisOwnersDad, I needed a chuckle this morning!

And ya look younger being "clean cut," Mr Hilton!

Happy New Year to you all!

Cheers! M2

[TheSilkySmooth]

I miss the beard!

[Yaris Hilton]

Took a bit of getting used to for me, too. :biggrin:

[detroiter]

Is anyone elses yaris idling a bit higher even when it's fully warmed up, as compared to when it's a hot summer day and the idle of the car is very low when it's warmed up? Seems like my Yaris keeps a higher idle when it's cold out as compared to a summer day, even after it's fully warmed. Not a HIGH idle, just higher than if it's hot outside.

[Yaris Hilton]

Mine does for a good while after the "COOL" light goes out, but it's not actually fully warmed up. After a good long drive, it falls back to a hair over 600 RPM. In a cooler place (it's 19 F here this morning), it might not drop back to normal idle speed.

[docB]

If you have the air control set to defrost or defrost/floor, the air conditioning will cycle. That will raise the idle.

[hpvampiress]

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.

Ah! That's probably why my gas mileage has dropped so much lately! Along with winter road as well, of course.

[YotaYaris]

I filled up this morning at one of my normal spots and what did I see on the pump.....
10% ethanol
That must be why I am down to 39MPG on average. That and more city driving has made me lose about 3-5MPG.

[devinlamothe]

I filled up this morning at one of my normal spots and what did I see on the pump.....
10% ethanol
That must be why I am down to 39MPG on average. That and more city driving has made me lose about 3-5MPG.

At least you don't have 15% everywhere ... it really eats your mileage. :frown:

[MadMax]

Yeah, I am also in San Antonio and I can't find gas without ethanol anywhere...

Cheers! M2

[Yaris Hilton]

At least you don't have 15% everywhere ... it really eats your mileage. :frown:

Do you have E15 in Canada?

[devinlamothe]

Do you have E15 in Canada?

Yes, at most of the stations where I live it's all E15. There are some with just E10 but not many.

[captainm27]

I know every car suffers MPG drops in the winter. But why is that? Is it because of the winter blend type of fuel being used? Or does an engine use more gas to stay warmer during the coler months? I drive my Yaris the same gentle way I do in the winter as I do during the warm spring days (with the exception of snow storms, etc.) I never see my RPM's going so much higher to suggest using more fuel. Does the engine use more fuel, even though it is keeping the RPM's at the same levels? Or is RPM just not a good indicator of how much gas is being used?

[Bob_VT]

Winter blend fuel, you use the heater (electric more), and in my case I have 4 snows mounted........ not too mention there is more resistance on the roads with slush and snow...... longer warm-ups.....

I usually average 36-38 in the winter and during real bad weather as low as 32

[captainm27]

I can see the winter blend fuel, that's what I think is affecting the most. I didn't know the heater requires that much more energy. During the spring and summer, I have my fans / AC blowing all the time. I usually don't warm up the car. Just turn on, shift to drive, and go. I can understand the slush and snow, but for the most part, here in NJ, when it snows, by the next day most roads are cleared. Hmm......

[Bob_VT]

Well, my "cool" light takes longer to turn off in the winter so the engine is not up to temperature as fast. The tires do not expand and heat up in the winter either.

[b_hickman11]

Your engine likes warm and hot air to be brought into it from the intake. The hotter it is outside, the better mpg's you will get. I recorded my best mpg on a day it was 105+ degrees outside.

[Hershey]

winter is good for nothing :thumbdown: . :frown:

[Hard_Yaris]

Here in Edmonton We get good week long cold snaps of -20C.

I never let my car Idle long, and have never had to plug it in even at -35C... It started with a few more turnovers.

My question would be: Would it help with millage to have a warmer engine bay with temperatures of -20 and lower?
I find my water Temp to be around 85C when its that cold.

[MadMax]

Your engine likes warm and hot air to be brought into it from the intake. The hotter it is outside, the better mpg's you will get. I recorded my best mpg on a day it was 105+ degrees outside.

Maybe that explains the good mileage I got this past summer, when we had all those 100+ degree days...

I can't wait for those days to return!

[Hard_Yaris]

So in this case Hot Air is Good!

[BailOut]

Your engine likes warm and hot air to be brought into it from the intake. The hotter it is outside, the better mpg's you will get. I recorded my best mpg on a day it was 105+ degrees outside.
Precisely. This is why many of us hypermilers block our grilles in the cold months, and why some also set up DIY warm air intakes.

[SQUARE HEAD]

My MPG almost always drops in winter. So far I'm seeing 2mpg less than summer.

MY LITTLE MULE USED TO GET AT LEAST 40MPG BUT SINCE THE COLD WEATHER MY MPG IS NOW DOWN TO 34--35MPG...SAME DRIVING HABITS ANY SUGGESTIONS??

[127.0.0.1]

MY LITTLE MULE USED TO GET AT LEAST 40MPG BUT SINCE THE COLD WEATHER MY MPG IS NOW DOWN TO 34--35MPG...SAME DRIVING HABITS ANY SUGGESTIONS??

wait for summer

or throw a blankie in front of the radiator

[Twistoffate0817]

When does the Northeast switch over to summer gas?

[Hershey]

usually in APRIL . Flowers bloom as do gas prices .

[docB]

When does the Northeast switch over to summer gas?

HA Ha ha

We don't have summer and winter blends any more. All the gas is cut with ethanol all year round. The alcohol just cuts your milage and raises the oil company profits. The environmental benefit just doesn't make this a good proposition. Flex fuel vehicles are as big a joke as HEVs.
doc

[docB]

I know every car suffers MPG drops in the winter. But why is that? Is it because of the winter blend type of fuel being used? Or does an engine use more gas to stay warmer during the coler months? I drive my Yaris the same gentle way I do in the winter as I do during the warm spring days (with the exception of snow storms, etc.) I never see my RPM's going so much higher to suggest using more fuel. Does the engine use more fuel, even though it is keeping the RPM's at the same levels? Or is RPM just not a good indicator of how much gas is being used?

Everything needs to warm up. Oil, grease, water, and the passengers. All that heat plus wipers and defrosters use up extra fuel. The DEF mode for the HVAC runs the air conditioner, too. The snow on the road offers a tremendeous drag that needs to be overcome.
doc

[docB]

Your engine likes warm and hot air to be brought into it from the intake. The hotter it is outside, the better mpg's you will get. I recorded my best mpg on a day it was 105+ degrees outside.

Was this mileage determination made with a Scan Gage or be refilling the tank?
doc

[b_hickman11]

Was this mileage determination made with a Scan Gage or be refilling the tank?
doc

By refilling the tank with the last bar started blinking and divided miles driven by amount of gas filled.

[b_hickman11]

HA Ha ha

We don't have summer and winter blends any more. All the gas is cut with ethanol all year round. The alcohol just cuts your milage and raises the oil company profits. The environmental benefit just doesn't make this a good proposition. Flex fuel vehicles are as big a joke as HEVs.
doc

Still have it here in Texas....

[Yaris Hilton]

Summer and winter blends aren't about ethanol vs. no ethanol. It's the boiling range of the gasoline part. In the winter they use a lot more butanes and pentanes, which give more vapor pressure for easy cold starting. In the summer the butanes and pentanes are way down, and there are more of the heavier, high boiling hydrocarbons to reduce vapor locking and evaporative emissions.

[Hershey]

Everything needs to warm up. Oil, grease, water, and the passengers. All that heat plus wipers and defrosters use up extra fuel. The DEF mode for the HVAC runs the air conditioner, too. The snow on the road offers a tremendeous drag that needs to be overcome.
doc would think the cold could affect wheel bearing grease as well . Making for more resistance . No ? :iono:

[Uber_Otter]

Dallas just switched back over to summer gas. I think. Got a 3 mpg gain on my last tank. Drove the same. Maybe they use Daylight savings as the cutover.

[Yaris Hilton]

Might've had a difference in your fill levels at the beginning and end of that tank, or a different driving profile. It's a little early for the change, I think. (It's still Winter.)

[docB]

It is great to track mileage. The big thing that really tells the whole picture is to keep track of all the fuel that goes into the tank and divide that into the mileage on the odometer. Then the amount you got back into the thing on a refill is a moot point. I made a small excell spread sheet. I keep track of the date, the odometer reading, the quantity of fuel (all the decimal places on the pump), the dollar amount and where I got it. If there are odd circumstances, I keep a side note. I track maintenance items here, too. The sum of the cost of the fuel is tracked along with the total gallons used. This is the number that I divide into the total miles on the car. I update the total fuel economy at the government EPA your mileage site. I have been over 39 mpg since I picked up my cash for clunker the last day of August last year. The max was a little over 44mpg and the low is probably in the high 20s. By the way, a 1994 Ford Escort Wagon 5-speed I bought new average just over 35 mpg over the time I owned it. I don't place a lot of faith in the instantaneous readings the cars provide. I think by brothers full size Dodge pick-up could only get 99mpg on a railroad flat car...lol
doc

[b_hickman11]

It is great to track mileage. The big thing that really tells the whole picture is to keep track of all the fuel that goes into the tank and divide that into the mileage on the odometer. Then the amount you got back into the thing on a refill is a moot point. I made a small excell spread sheet. I keep track of the date, the odometer reading, the quantity of fuel (all the decimal places on the pump), the dollar amount and where I got it. If there are odd circumstances, I keep a side note. I track maintenance items here, too. The sum of the cost of the fuel is tracked along with the total gallons used. This is the number that I divide into the total miles on the car. I update the total fuel economy at the government EPA your mileage site. I have been over 39 mpg since I picked up my cash for clunker the last day of August last year. The max was a little over 44mpg and the low is probably in the high 20s. By the way, a 1994 Ford Escort Wagon 5-speed I bought new average just over 35 mpg over the time I owned it. I don't place a lot of faith in the instantaneous readings the cars provide. I think by brothers full size Dodge pick-up could only get 99mpg on a railroad flat car...lol
doc

Sounds like a lot of extra work just to find your mpg.....

[BailOut]

Sounds like a lot of extra work just to find your mpg.....
That's because he's tracking more than just MPG. :wink:

[b_hickman11]

That's because he's tracking more than just MPG. :wink:

Sounds like he needs to track what winter gas is.....