[AT] Ram fuel mileage

Sat Jun 14 04:57:41 PDT 2014

Seasonal difference in fuel economy arises from a combination of factors,
each contributing a minor amount but they all add up to a noticeable amount.

Rolling resistance increases at cold temperature.  This relates to
increased viscosity of driveline lubricants plus decreased flexibility of
the tires.

Air resistance increases at cold temperature.  Density is higher therefore
drag is higher.

Engine warmup takes longer and therefore more fuel is burned during that
period.  This relates to the heat contained in the block and cooling system
and also relates to lubricant viscosity.

Electrical loads tend to be higher.  HVAC fans draw surprising amps, plus
heated seats, rear window defrosters, headlights, etc.

SOME people idle their cars to prewarm them in cold weather, especially
with the rise of those wireless remote-start systems.  Obviously doesn't
apply if this is not your habit.

If you drive a turbocharged and intercooled vehicle, the intercooler
becomes significantly more efficient at cold temperatures and you will feel
an increase in power.  This is NOT an increase in efficiency.  More power
comes from additional air stuffed into the cylinders and therefore more
fuel can be burned.

SO

On Fri, Jun 13, 2014 at 5:10 PM, Spencer Yost <yostsw at atis.net> wrote:

> Hey herb,
>
> It's a 2011 VW Golf TDI 2door hatchback with the manual 6 speed
> transmission.   One of the last of the Wolfsburg, Germany cars.
>
> My commute, each way, is 45 mile interstate and 18 miles of country roads
> with just a half dozen stop signs.
>
>
> In pure city/suburb, I still get 37-39mpg winter/summer
>
> I have never understood the difference in the seasons.   My only
> hypothesis is general thermal efficiency.
>
> Hope this helps,
>
> Spencer
>
> Sent from my iPhone
>
> > On Jun 13, 2014, at 15:29, "Herb Metz" <metz-h.b at comcast.net> wrote:
> >
> > Have not been very attentive of some posts, but I sure noticed the 44 and
> > 47.  Your VW Golf diesel is what year? what transmission? sedan? your
> > principal transportation?  Engine size? Etc?
> > Herb
> >
> > -----Original Message-----
> > From: Spencer Yost
> > Sent: Friday, June 13, 2014 3:04 PM
> > To: Antique tractor email discussion group
> > Subject: Re: [AT] Ram fuel mileage
> >
> > Thanks for the clarification.  I thought the urea was for the DPT and
> urea
> > was somehow burned during regen.   I did not realize it was NOx reduction
> > instead of the detune.
> >
> > I average 44mpg in the winter, and 47mpg in the summer (fill-up
> > calculations - not computer) with my VW golf diesel.   I can't imagine
> > Exhaust Fluid raising it much more than 3% and am very glad I have a
> spare
> > and no exhaust fluid.
> >
> > BTW:  Am I the only one who think exhaust fluid sounds like the old
> "blinker
> > fluid level" joke?  (-:
> >
> > Spencer
> >
> > Sent from my iPhone
> >
> >> On Jun 13, 2014, at 10:36, Stephen Offiler <soffiler at gmail.com> wrote:
> >>
> >> Most of the diesels available new in the USA are using DEF (that is
> Diesel
> >> Exhaust Fluid and is the common name for the urea that Spencer
> mentioned).
> >> There are some exceptions in the VW TDI lineup.  It's all a matter of
> >> meeting the US emissions specifications.  If they can tune (or detune)
> the
> >> engine to meet emissions without DEF, then they might choose that route.
> >> For example, VW detunes the Jetta TDI and omits DEF, resulting in
> slightly
> >> lower fuel economy versus the Passat TDI which does use DEF.
> >>
> >> DEF controls oxides of nitrogen, not particulates.
> >> http://en.wikipedia.org/wiki/Diesel_exhaust_fluid
> >>
> >> Yes, the new Ram Ecodiesel engine requires DEF.  Ram claims 11 gallons
> per
> >> 10,000 miles which is 909 miles per gallon DEF. Some Internet forum
> >> discussion reports actual consumption rates slightly above 1000 miles
> per
> >> gallon DEF.  1000 is a nice round number.  NAPA sells 2.5 gallon jugs
> for
> >> $14 (= $5.60 per gallon DEF) but it is starting to show up at gas
> stations
> >> for reportedly as little as $3 per gallon DEF. Let's just call it a nice
> >> round $5 per gallon.  That's an additional expense of $5 per 1000 miles
> on
> >> top of fuel cost.  At 25 MPG and $4 per gallon for fuel, it costs $160
> for
> >> fuel to drive 1000 miles, so just make that $165.  If you were to think
> of
> >> DEF like some sort of fuel surcharge, it works out to 3%.
> >>
> >> As a side-note, particulates are controlled with a Diesel Particulate
> >> Filter (DPF) which is built sort of like a catalytic converter but it
> >> doesn't do any catalyzing.  It traps the particles and then periodically
> >> heats WAY up (650C plus, which is 1200F plus) to burn the collected
> >> particles down to ash.  This is called DPF Regeneration.  It will happen
> >> naturally if you drive hard enough to get it that hot; otherwise it will
> >> be
> >> forced to happen periodically (about every 500-1000 miles) by injection
> of
> >> extra fuel.
> >>
> >> SO
> >>
> >>
> >>
> >>
> >>
> >>> On Fri, Jun 13, 2014 at 9:08 AM, Spencer Yost <yostsw at atis.net> wrote:
> >>>
> >>> One side note.  The diesel they build for the Chevy Cruz American
> market
> >>> uses urea injection for particulate control.    The urea tank is just
> >>> another tank to fill and eliminates the spare tire.   They give you a
> can
> >>> of fix-a-flat instead!
> >>>
> >>> Not sure about about the larger engines.   I was only looking at cars.
> >>> In the end my wife decided to keep her VW diesel jetta (fuel is used
> for
> >>> particulate control) and run it into the ground.  Which is proving hard
> >>> to
> >>> do (-:
> >>>
> >>> Spencer
> >>>
> >>>
> >>>
> >>> Sent from my iPhone
> >>>
> >>>> On Jun 13, 2014, at 0:55, "Sewell, Steven" <sewell at ohio.edu> wrote:
> >>>>
> >>>> Dennis keep us updated on the truck. The same diesel is an option in
> the
> >>> Jeep Grand Cherokee.  I've been looking at the Jeep for our "car"
> >>> replacement in the next year.
> >>>>
> >>>> Steve Sewell
> >>>> Albany, Ohio USA
> >>>> sewell at ohio.edu
> >>>> sewell at atis.net
> >>>> ________________________________________
> >>>> From: at-bounces at lists.antique-tractor.com [
> >>> at-bounces at lists.antique-tractor.com] On Behalf Of Dennis Johnson [
> >>> moscowengnr at yahoo.com]
> >>>> Sent: Thursday, June 12, 2014 12:56 PM
> >>>> To: at at lists.antique-tractor.com
> >>>> Subject: [AT] Ram fuel mileage
> >>>>
> >>>> All,
> >>>> The mileage numbers were calculated after entering gallons and miles
> >>> into a spreadsheet. I also did trip average for the long trips via
> >>> spreadsheet. I also do a running 3 tank average to check for incomplete
> >>> fill ups, etc.
> >>>> I do not have a good way to account for idle time, etc. truck records
> >>> idle vs drive time, but not sure exactly what to do with this other
> than
> >>> keep for general information.
> >>>> I am guessing the screen numbers on the dash are a little bit high,
> but
> >>> still impressed with the truck.
> >>>> Thanks
> >>>> Dennis
> >>>>
> >>>>
> >>>> Sent from my iPad
> >>>> _______________________________________________
> >>>> AT mailing list
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> >>>> _______________________________________________
> >>>> AT mailing list
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> >>>
> >>> _______________________________________________
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