PSA: beware of lower MPG during winter months

[r11]

For those about to live through 1st winter with TDIs:

4-5 MPG drop is to be expected for those of s north of say Wash DC.
Winter formulation fuel and colder weather both combine for this effect.

While on it - due to incredible thermal efficiency of our engines, dont try to get em warmed up on a cold winter day by idling - it wont move the needle, the car needs to be driven to get to temp.

It is almost counter-intuitive - idling will hurt it more than starting it up and driving away.

 

[Rico567]

Mileage drop in winter will occur with all cars- the use of cheap and more volatile fractions in winter gasoline produces similar results (and don't shop around, it's a federal requirement). Also, the owner's manual for all of our cars says the same thing as the last two sentences: start the car and drive off, don't idle. This is why we will not be using the remote start on our car.

 

[740GLE]

Also the shorter the drive the more sever the mpg hit will be.

I have no problem hitting 45-48 mpg tanks in the winter jetta or passat, we just have to do our normal 140 mile treck to visit family in Maine.

But I'll get around 35mpg in my 2 mile commute to work.

 

[pparks1]

Thanks for the warning. I've always lost MPG's on any car that I have owned in the winter. Air is more dense when it's cold, and thus it takes more fuel to mix with the increased air density and thus mileage goes down.

I never let the car idle in the winter, it's part of the reason that I don't really understand the value of remote start in the winter. What we should have is remote heated seat activation and electric heat activation to melt ice off the windows.

 

[compu_85]

post injection to warm up the cats
AND
more frequent regen cycles
AND
several hundred watts of heaters for the AdBlue system
AND
over a kiliwatt of power for the cabin aux heater
AND
several hundred watts of power for the climate control, heated seats, etc
AND
the lower BTUs of winter fuel
...

will all contribute to killing your economy in the winter time.

-J

 

[VeeDubTDI]

The shorter your commute, the worse the hit will be.

Also a fair warning note for winter forum moderation... all POOR FUEL ECONOMY threads will be merged together. I don't think any of us feels like looking at thread after thread about why fuel economy is poor, what to do to get it to stop being poor, how much VW sucks for this that and the other thing, etc. (All of this was discussed last year anyway - if you want to read it, search for last year's threads.)

 

[inthered]

Does activating the heated seat really decrease your fuel efficiency? How much of a draw is it on the electrical system? I never noticed an issue with my 05 Jetta.

 

[Rico567]

Does activating the heated seat really decrease your fuel efficiency? How much of a draw is it on the electrical system? I never noticed an issue with my 05 Jetta.

Well, heated seats draw a certain number of watts, and I'm sure that can be translated into fuel consumption in some torturous math....but I don't see that as the point. We bought the SEL Premium because we wanted the DSG, even though it's not quite as efficient as the manual. That's a tradeoff. Same with heated seats. I am most emphatically not going to leave the heated seats I paid good money for off on a 10 degree morning just because it might add up to an ounce or two of fuel at some point....and the same for A/C or any other power-consuming accessory.

 

[compu_85]

The heated seats probably draw 50 watts each.... I guess not that much really. But it does all add up!

-J

 

[pparks1]

My plan is to focus on just driving downhill in the winter. I will simply pay to have my car towed back to the top. That should keep my fuel mileage right up there and help the local tow truck economy.

 

[TDI in MT]

This will be my first winter with the Golf. No FrostHeater, no heated seats either. Though it usually lives in the garage, I will park it outside for a few nights when the temp is going to get to -20F overnight just to see how it handles the cold. I'll wait until daylight to start it so the racket won't wake the neighbors.

 

[jck66]

People in Montana have neighbors??

 

[Lightflyer1]

Yes N. Dakota, S. Dakota, Wyoming, Idaho and Canada.

 

[TomB]

Except for those in areas that require continuous A/C usage during the summer like Vegas. We don't get winterized diesel and we don't need the A/C anymore so we should see an improvement.

I know, most of the USA is not in this situation, but had to point it out.

 

[JSWTDI09]

Except for those in areas that require continuous A/C usage during the summer like Vegas. We don't get winterized diesel and we don't need the A/C anymore so we should see an improvement.

Nevada does get "winterized" fuel. Granted, it is not as heavily winterized as in Minnesota (for example), but it is winterized. I get my best mileage in the spring and fall when we still get summer fuel but AC is not necessary. Every state except Hawaii gets some amount of winterization, but it varies from state to state. Remember, we do have mountains in Nevada where it can go well below freezing. Without winterization, there would be a lot of dead (gelled fuel) diesels parked at the ski lodge on Mt. Charleston every spring.

Have Fun!

Don

 

[Rico567]

I can understand why Hawaii gets fuel that hasn't been winterized, but I think it's highly unrealistic to think that the vendors are going to custom treat this fuel on a state-by-state basis.

 

[JSWTDI09]

I can understand why Hawaii gets fuel that hasn't been winterized, but I think it's highly unrealistic to think that the vendors are going to custom treat this fuel on a state-by-state basis.

The law is the law. Diesel fuel is always treated on a tanker truck by tanker truck basis (far more granular than state by state). Below are pour point specifications for every state. Some states even have more than one region or zone, each with different specifications (like CA and AK). Oil companies have to adjust the amount and type of additives they put into our fuel as the seasons change. Remember D2 (raw diesel fuel) pretty much never changes, it is the additive mixture that is put into the tanker truck at the terminal on the way to your station that varies from season to season and/or from company to company.

Note: This page is old information. Some numbers have probably changed, but the general idea is still true.

http://www.tdiclub.com/TDIFAQ/TDiFAQ-10.html

Have Fun!

Don

 

[Rico567]

Wow. I had no idea it was so involved. Being new to the diesel world, I had a general notion that I should probably treat my fuel if I were caught, e.g., visiting our relatives on the Gulf Coast in Alabama during the Winter then driving home to Illinois on fuel bought down there. But this is something else again.

 

[psd1]

Yawn!

Except for those in areas that require continuous A/C usage during the summer like Vegas. We don't get winterized diesel and we don't need the A/C anymore so we should see an improvement.

I know, most of the USA is not in this situation, but had to point it out.

Incorrect in more ways than one, especially with the average temperature in December in Vegas being 57*. Do you really expect me to believe that you run the air at an OAT of 57? Alot of the northern part of the state of NV experiences temperatures down into the teens, ever been to Tonopah in December?

I can understand why Hawaii gets fuel that hasn't been winterized, but I think it's highly unrealistic to think that the vendors are going to custom treat this fuel on a state-by-state basis.

Incorrect.

The objective of the OP's post and making it a "sticky" was to avoid a bunch of questions in the next couple of months about MPG decline. The fact that fuel is winterized, and winterizations effect on MPG has been covered many, many times and I am amazed at peoples "knowledge". Once again, if you don't know the correct answer, it's usually best to not offer advise.

 

[Rico567]

<snip>

Incorrect.

The objective of the OP's post and making it a "sticky" was to avoid a bunch of questions in the next couple of months about MPG decline. The fact that fuel is winterized, and winterizations effect on MPG has been covered many, many times and I am amazed at peoples "knowledge". Once again, if you don't know the correct answer, it's usually best to not offer advise.

Yes.

1. My post was pointed out as incorrect once already.

2. It's not "advise" (sic), it's an opinion. There's a difference.

3. I'm new to diesel ownership, this is one of the ways I'm learning about it, i.e, my incorrect opinions are revised. If I can deal with it, the rest of the people on this forum had best learn to deal with me!

 

[TomB]

Extra Yawn

Incorrect in more ways than one, especially with the average temperature in December in Vegas being 57*. Do you really expect me to believe that you run the air at an OAT of 57? Alot of the northern part of the state of NV experiences temperatures down into the teens, ever been to Tonopah in December?




Incorrect.

The objective of the OP's post and making it a "sticky" was to avoid a bunch of questions in the next couple of months about MPG decline. The fact that fuel is winterized, and winterizations effect on MPG has been covered many, many times and I am amazed at peoples "knowledge". Once again, if you don't know the correct answer, it's usually best to not offer advise.

LOL! Just being rude again, huh?

I will NOT be using A/C in the winter and I will therefore see an improvement in MPG compared to the summer with it's 100% A/C usage. 57F does not require A/C.

I can run B100 down into the 20's without issue. When I talk about cold, I am talking -20F in the Cascade Mountains, not the teens. It is at those extreme temperatures that the fuel additives become critical. Even with the treated fuel I had to add the Power Service products to ensure good starts on winterized D2.

Fuel distributors do NOT add anything more than absolutely necessary and the refineries in Washington State are most definitely adding different additives than those in Southern California. Fuel is treated differently regionally. Those areas you talk about in NV are most likely fed from the Northern California refineries where Vegas is Southern California.

 

[psd1]

LOL! Just being rude again, huh?

I will NOT be using A/C in the winter and I will therefore see an improvement in MPG compared to the summer with it's 100% A/C usage. 57F does not require A/C.

I can run B100 down into the 20's without issue. When I talk about cold, I am talking -20F in the Cascade Mountains, not the teens. It is at those extreme temperatures that the fuel additives become critical. Even with the treated fuel I had to add the Power Service products to ensure good starts on winterized D2.

Fuel distributors do NOT add anything more than absolutely necessary and the refineries in Washington State are most definitely adding different additives than those in Southern California. Fuel is treated differently regionally. Those areas you talk about in NV are most likely fed from the Northern California refineries where Vegas is Southern California.

You're correct, I misread your post. Your MPG may stay the same. I apologize.

Your assumption about distributors may or may not be correct, in Oregon they are required to run the winter mix starting Oct 15th even though "most" of the state wont need it until December. The state has a mandated cold pour point the distributors must meet.

 

[carlrx7]

Yall make me like SC and FL more and more every winter! hehe. Enclosed garages can help reduce the 'mpg hit' as well.

 

[PassatSE4me]

This winter fuel thing is going to kill my Fuelly average.

 

[compu_85]

Yup. But at least you can enjoy being warm in the car!

Consider you could be driving an old indirect injection diesel which also makes great heat in the winter... and also gets bad fuel economy all the time

-J

 

[PassatSE4me]

Consider you could be driving an old indirect injection diesel which also makes great heat in the winter... and also gets bad fuel economy all the time

All I really need to consider is that I'm not driving a 12mpg F250 anymore. I'll take mid to high 30's all winter long, heat or no heat.

 

[unixb0y]

Is there an additive that will offset the poor winter mileage of winterized fuel?

 

[jck66]

I haven't found one. But consider that it's more than just the fuel that contributes to the loss in mpg.

 

[VeeDubTDI]

Is there an additive that will offset the poor winter mileage of winterized fuel?

No there is not. As jck66 said, there is more to it than just the lower BTU content of the fuel.

 

[DubFamily]

I did not take a MPG hit through the winter last year... We'll see if I can pull it off again this year or not