Winter Mileage

[jorpet]

Double D, I noticed the drop as well when they first switched to the winter diesel here. I started adding cetane boost and my last tank was nearly at 50 MPG. I did a bit more highway driving that tank and that might have helped.

I am now using Union 76 and it is better than the Texaco I tried. Rahsut has had good luck with Cheveron (that is what you are using if I remember correctly).

The current tank is empty and I will be filling on the way home this afternoon. I expect less mpg on this one since I had to show my father-in-law and brother-in-law that not only can the car get 50 mpg, it can get to 75 up a hill with all of us in it

.

 

[Dante]

Thanks ClydeCPA (Hey, I'm a CPA, too

) and Jorpet. I think I descreened and installed my K&N in October (right after my best tank, if I recall correctly). I've also been using 76 fuel and Amsoil Cetane Boost for the last couple tanks. Given my commute, I was satisfied with 44-45 mpg, but not 41

I'll try a different service station--maybe the 76 that advertises premium in SoDo.

 

[jorpet]

DD I am using the 76 in SoDo on 4th Ave. There are always multiple people fueling diesels there and of course the big rigs.

 

[Turbo Steve]

Depending on how cold your part of the country gets, you just as well subtract anywhere from 10% - 20% off your summertime MPG for a while and try an not get too depressed about it.

Winter fuel is the pits!

 

[Dante]

I just refuelled for the eleventh time. My best mileage (51.44 mpg) occurred back in october, and I got 48.54, 44.02, 45.46 and

41.41 since then.

My driving style and tire pressure has been consistent. I used cetane boost on the last 2 tanks. The only other major variable, and the one I think is responsible for the poor mileage on the last tank is cold weather. My car has taken much longer to warm up lately, and I think this has a large impact because my commute is short (12.5 mi one-way). About 25% is city driving. The rest is on the freeway--usually 60 mph in the morning and stop-and-go at night.

I thing the cold weather and/or winterized fuel are responsible. Other opinions?

 

[pumpadoosa]

Dante, I have not hade the same effects as you, but at about the same time everyone started winterizing the fuel, I switched to a K&N air filter and started using cetane boost and Diesel Kleen. My normal driving (mixed at about 50 hwy/50 city) has stayed about the same in fuel economy, around 46-47 mpg. I hope my enhancements have offset the winterized fuel. If so, I should hit the 50's when warm weather comes back around.

Johnny
'00 Jetta TDI

 

[jorpet]

Turbo Steve, it is a chilly 36 F here this morning and it should hit nearly 50 F by this afternoon. We did have a week that actually had some nights that dipped into the high 20's

.

DD, I saw the drop using the Texaco, but have seen a marked improvement with the Union 76. My first tank from 76 gave me a 10% improvement over Texaco. The second one that I just finished yesterday gave me a 5% improvement over Texaco.

The first tank had two trips to the pass so a little more highway mileage. The last was all commuting to work and around town with a lot of short trips (5 miles or less).

Check out Jorpet's Mileage to see what and where the gas is coming from.

[This message has been edited by jorpet (edited December 29, 2000).]

 

[Dante]

I think it is the combination of (1) winterized fuel, (2) the cold snap (by Seattle standards) Jorpet mentioned and (3) my short commute. When it's cold my car doesn't reach the normal operating temperature until I'm half way to work--that's got to hurt my fuel efficiency. In the summer the car was warmed up by the time I got to the freeway. I'm thinking about blocking 1/2 the radiator and seeing what happens.

 

[Turbo Steve]

Just filled up while on a date with my wife and benefitted from 47.1 MPG on mostly city driving with Amoco PowerBlend at 1.899 per gallon.

[This message has been edited by Turbo Steve (edited December 29, 2000).]

 

[Heinz57]

Just got back from a 750 mile jaunt to Depoh Bay in Oregon and managed 49.2 MPG with 5 people and loaded to the hilt with luggage, cruisng at 75 MPH and up/down across Oregon . I did fuel up at Flying J in Federal Way and use redline 85 diesel additive for the last 25K. Even with Chip and Tuning box I seem to be averaging 48-50 MPG at 20% city and 80% freeway.

------------------
2K Golf GL TDI
White/BLack
UPsolute Chip&Tuning box Descreened, K&N and rear fogs/euroswitch

 

[jayb79]

Dante,
My millage did the same thing on my NB. The mileage on my A3 jetta never got as high as the NB but it also did not drop this much with the cold weather.

 

[Turbo Steve]

Must have gotten ahold of some good Amoco PowerBlend because my last tank of 50/50 city/highway driving yielded 47.9 MPG.

 

[GotDiesel?]

What are they charging for the Unocal Premium down in SoDo?

The Chevron on Aurora in Lynnwood is still at $1.799

Just made a trip down to Sacramento and back this past week. Averaged ~70 mph and got just over 50 mpg. Not bad if this is winterized fuel.

I got some fuel about 40 miles north of Sacramento on I-5 at a Pilot fuel stop. Seems to be nice stuff. Lights off without the customary puff o' smoke in the morning.

Amazingly, it was only $1.729. Virtually everywhere else I saw diesel it was over $1.80.

 

[Daryl]

Up here in the great white north we get the same problem. I have noticed a big drop since the temperatures have gone down and the winterized fuel has hit the market. I am in the high 30's and low 40's as far as MPG go.

I normally average in the high 40's (mixed driving and a heavy foot) I just started to use powerservice arctic antigel with cetane boost. I hope it helps. Temperatures here have been in the -20 range. Pluged in or not my ride still fires up with no problems.

Cheers...Daryl

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2001 Indigo Golf GL TDI 5spd
I am a TDI Addict and there is no cure.

[This message has been edited by Daryl (edited January 02, 2001).]

 

[mfd]

Just topped off my 2K NB. After a year of ownership and 24k miles, I've averaged 52 overall - with a best trip run of 57.6 during a trip to the Mount Washington in NH. Now..reality sets in and now am averaging 47 mpg since the winter set in. (80/20 HGWY/LOCAL)..and loving every minute of ownership!

 

[jorpet]

ThinkDiesel,
The station in SoDo has been bouncing between 1.759 and 1.799. I think the last tank was back down.

 

[Dante]

Sounds like it's worth the drive. The Unocal on Pill Hill (nearest me) was charging $1.89 last week. I'll stop by the SoDo station and top-up next weekend.

 

[Boundless]

There is a definite correlation between weather and TDi MPGs. I keep continuous records on my TDi and the graph of MPG vs. Calendar Date shows a sine wave that shows lowest MPGs in the cold weather and highest MPGs in the warm weather. The TDi seems to be much more sensitive to the weather than my gasser. I don't believe that winterized fuel is solely the cause. Anybody have any other ideas? Can we conserve heat like the big truckers?

------------------
Boundless

 

[Craig]

I have been saying this for a year now. Outside temperature is one of the MOST important factors for lousy winter mileage. Winterized diesel will give you at most a 10% reduction in mileage. Add cold temperatures and you are hit again. If you could do this test you would be amazed:

Drive 500 miles on winter diesel at 40F and compute mileage.
Drive 500 miles on winter diesel at 0F and compute mileage.
You will be shocked.

The effect is even worse if you do a lot of start and stop short trips in the city.

(P.S. I have noted a reverse effect in summer with summer diesel although not as pronounced. I get better mileage at 80F than I do at 60F.)

In case you think only diesel cars have this decrease with temperature, read this: http://forums.vwvortex.com/vwbb/Forum4/HTML/019159.html

 

[Autopilot]

I am another anal retentive mileage record keeper. I have found my mileage go from an average of 49 through the summer to about 41 to 42 during this winter. (By the way, this is a much more normal winter in Minnesota than the past 3 or 4 as far a temperature goes).

Using 51 mpg peaks as a baseline, winter is showing a decline of about 19%.

I tracked my '85 Jetta gasser for 13 years and like Boundless said, the mileage formed an almost perfect sine wave, with peaks in July-August and the valleys in Jan-Feb. The peaks were all about 35 mpg and valleys at 27-28mpg. Using the summer mileage as the baseline again, that is a difference of 20%.

I only have one year of data on the new Jetta, but this is certainly in the same order of magnitude as my old gasoline powered 1.8 liter VW.

I completely agree with Craig that ambient temp is by far the most significant mileage variable I encounter, providing the car is reasonably to spec for tires pressure, tuning etc. Most of my mileage is put on in 27.5 mile highway chunks (my commute to work and back), so the engine is fully up to temp for most of the miles I drive, both winter and summer. I doubt that an engine pre-heater would significantly alter my mileage. In fact, I had a pan heater in the old Jetta that was used quite frequently, both at home and at work during the last 5 or so winters, without an effect on mileage. (Helped starting though).

 

[Boundless]

Okay, how about this.... what if we put a cover in front of the grill like the big rigs do to restrict the flow of cold air into the engine compartment and, doctor the air filter box so that air is taken from the engine compartment (warm) instead of from the outside (cold). It seems we need to conserve heat to keep our TDi's efficient in the cold weather. Maybe even block cooling air from the intercooler during really cold weather. Whaddya think?

------------------
Boundless
1997 Jetta TDi

 

[Zwei Bora Tdi]

I get 42mpg and the weather here is in the 30's to 40's average. I saw better in the summer. I don't know if they winterize the diesel fuel over here. There are however, 2 types at the pumps, one for cars and the other for trucks. Haven't noticed any difference between the two.

 

[GregR]

The reduction in mileage started in October for me. Since last March, my mileage has been above 50 mpg. In October and November my mileage dropped to 48-49 mpg. Over the last few very cold weeks, it has dropped to 47 mpg.

------------------
98 Jetta TDI, 91,000+ miles, Highest mpg 53.9

 

[Dezl Don]

Is this the CPA thread? I be one too.

I just got my all-time worst mpg this last 1/2 tank fillup. It's been real cold here (not like you southerners get). And virtually all the driving was stop-and-go city, very little highway. Result = 37.3 mpg. But that's better than the equivalent 12-13 mpg my wife gets in her gasmobile in the same conditions.

------------------
Dezl Don

 

[Dante]

I guess it figures that CPAs would buy TDIs with long-term economy in mind. I think I'm gonna go post a CPA survey in the General Discussion forum!

 

[Craig]

If you guys think your mileage is bad now, wait until the temperatures bottoms out later this month or Feb.

Boundless, if this would work it might make a case for using a cone filter in the cold, for the same reason our southern TDIers have concerns when it is very hot. In practice I don't think it will do much since the volume of air going into the engine would be too much to pick up any heat from the engine.

 

[Dante]

I refuelled at 1/2 tank and my calculated mileage is back up in the range I had become used to. Maybe I just got a bad tank of fuel.

 

[twig93]

Hi all ! I bought my '00 Jetta TDI in June of 2000. I have been a silent reader on this board until now.

I have noticed a significant drop in mileage in the last few months. I accept that it is partially due to the winterized fuel. I have a question about something else I am sure is contributing. I had my Jetta in for service at 10,000 mi. and complained of a loud rumbling from the tires. I was informed that they are worn out. They said there is a TSB out on the Good Years on the Jetta for premature wear. It will take 4-6 weeks to replace them . Are these worn tires contributing significantly to my poor mileage? I haven't actually calculated the mileage in some time, but do notice having to fill up at or around every 500 miles as opposed to between 600-700 previously.

 

[Zwei Bora Tdi]

Twig93, Quit doing burn-outs! And showing off! Seriously though, I have the Michelin green eco's or something. I can't reading about a recall. Check the Goodyear website or go to Tirerack.com and ask those dudes. Good luck!

 

[shirish_bh]

I filled up at Mijer's (Orion township) the other day and the diesel there smelled distinctly of Kerosene. The probably use it to winterize the fuel but that resulted in a noisy engine for me. It was good that my tank wasnt empty and I put only about 6 gal of the Mijer's stuff. I still have to see what mileage I get, but I guess it will be something like 41 MPG. I will NOT fill up at Mijer's again.