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VW Jetta TDI

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  • MrShift@EdmundsMrShift@Edmunds Posts: 43,664
    Keep in mind that EPA numbers were revised *downward* last year---you might remember the great distress this caused automakers.

    Once again, the auto mags logged their averages over many tens of thousands of miles, and *average* means that you clip off the edges of the bell curve in the data points---so those of you getting 25 mpg or 45 mpg are thrown out of the *average*.

    Also EPA does various testing cycles, some of which are not under ideal conditions for economy.

    I only bring this up so that some TDI future buyers are not disappointed by getting "only" 36 MPG. That's what you're supposed to get. If you get more, well, good on ya'.
  • eliaselias Posts: 1,836
    stands to reason , yes. My one data point is replicated tens of thousands of times by other TDI owners. Believe what you like! Or step up and drive a TDI and discover the truth yourself. You too will be just one more datapoint getting better mpg than EPA tests indicate.
  • 104wb104wb Posts: 38
    I looked into the new ratings a little bit when they came out, 2008MY I think? Previously, EPA fuel economy numbers were based on two fundamental test cycles which hadn't changed in many years (although adjustments had been made to the raw results, hence EPA 'adjusted' mileage). The new ratings were devised to include tests that represented more aggressive driving behavior / conditions. These three extra tests were adopted from the emissions side of the business. One of these added tests was a 'cold start / operating condition' test which diesel powered vehicles had never had to participate in on the emissions side, and so that data was perhaps not readily available to calculate the new EPA rating for 2008MY, maybe 2009MY Diesels. Transitionally, the EPA allowed any car to have the new rating based on the two original, traditional test cycles, modified by a new EPA formula that was based on empirical data from about 100 different cars, all but a couple of which were gasoline powered. Since there are some fundamental differences between how gasoline engines operate (normally stoichiometric, but 'extra' fuel added near full load or high speed or cold start - aggressive situations) and how diesel engines operate (always globally lean), it is quite possible that diesels opting to use the EPA formula instead of running all five tests might end up with a lower rating. I think by now, 2011MY, that the transition period would be over, but I'm not sure about that. It would be in the manufacturers best interest to post the best numbers possible, which would mean using all 5 tests, not the EPA formula based on a fleet of gasoline powered vehicles.

    My observation, based on 'estimates of drivers like you' on the EPA website, is that the average mpg for all diesel powered cars - VW, BMW, MB, Jeep - run closer to the 'hwy' rating than the 'avg' rating. Averages for gasoline powered cars are usually pretty close to the advertised 'average'.
  • MrShift@EdmundsMrShift@Edmunds Posts: 43,664
    edited July 2010
    I'm more inclined to believe the longterm auto magazine testing as more representative of real world averages. So many reports from all over the world can't be all wrong. That makes no sense. I can post from Canada, Australia and Europe but I'm not inclined to belabor the point.

    If it matters, a VW JSW forum seems to verify the 35-42 range as average.

    http://forums.tdiclub.com/showthread.php?t=260851

    The mags also verify that their averages are closer to EPA hwy than EPA city, so really, both sides of the argument have their points.
  • eliaselias Posts: 1,836
    fwiw all my personal data/experience with ~500k miles on 4 TDIs is with 2006 & prior TDI models. two were manual, one was slushbox, one was DSG.

    It's pretty clear both from the EPA as well as anecdotal reports that the 2009/2010 models get slightly lower mpg then the 06s & earlier - maybe because so few are broken-in yet.
    Or maybe because the newer models will never get as great EPA-highway-matching mpg as do the 2006 & prior models...
    best regards...
  • gagricegagrice San DiegoPosts: 28,680
    Don't forget the 2009 Jetta TDI is the mileage champ according to the Guiness Book of World records. So far no challenges including the Prius.

    Mr. Taylor and his wife, Helen, had completed a 48-state drive averaging 67.9 miles a gallon: 9,505 miles in 19 days, filling up only 13 times and spending a total of $371.03 for diesel fuel. That beat the Guinness record of 58.8 miles a gallon they set a year ago on nearly the same route in an almost identical 2009 Jetta TDI.

    One difference this time was the tires. The Jetta was fitted with Goodyear Assurance Fuel Max tires, low-rolling-resistance models that will be standard equipment on the 2011 Chevrolet Volt.


    http://www.nytimes.com/2009/09/13/automobiles/13MILEAGE.html

    They doubled the EPA estimate. Has any other vehicle come even close?
  • m6userm6user Posts: 2,897
    edited July 2010
    I saw a test of the new Hyundai Sonata that was done by a bunch of press types out in CA when the new model just came out. They were challenged to drive a certain route and get the best mpg they could. Excerpt follows:

    First place went to the team of Donald Buffamanti of AutoSpies and Jaime Florez of Ruedas ESPN with a 52.8 mpg rating that would even impress a Prius.

    The gold medal winners got more than just praise, however, as Hyundai Motor America CEO John Krafcik offered to treat anyone who could beat his personal time of 47.8 mpg to a private dinner.


    This is on a car that has an EPA average of 28mpg I think. They almost doubled the EPA average of 28mpg. However, when you consider that D2 is about 5-10%(my area is at 8% higher right now) higher price than reg. gas it is pretty much a wash in performance and cost.

    However, nobody drives anything close to like any of these people did on a normal basis so, while it's it's interesting, it doesn't mean a whole hell of a lot.
  • altair4altair4 Posts: 1,469
    I've been following this thread because of my interest in possibly purchasing a JSW TDI in the future. But I felt compelled to post a reply about the EPA mileage numbers. Currently, I'm driving a VW Paswsat, 1.8T, with the 5 speed tiptronic slushbox.

    The original EPA sticker gave the figures as 21 City, 25 Combined, and 30 Highway. The new formula gives the results as 19 City, 22 Combined, 28 Highway.

    I keep obsessive compulsive track of my mileage: over 75,000 miles, I've averaged 22.94, so I'm right on the new combined average. Highway trips, ranging anywhere from 200 to 425 miles, usually exceed 30 mpg. My record is 34.9 mpg across northern Ohio. This is all without any hypermiling techniques, and I'm usually 5 over the posted speed limit, and with the a/c running. So I see the EPA results for Highway as underestimated. City driving all depends on time of day, and traffic. Off-peak (non rush hour) is around 20. But stop and go in heavy traffic really kills the mileage with the turbo - I can easily dip to 17 mpg.
  • MrShift@EdmundsMrShift@Edmunds Posts: 43,664
    These are obviously hypermilers. This has little relation to 99% of all drivers. I could coast, short-shift, over-inflate tires, pick my routes, etc. and easily break EPA for my car, every time.
  • dwpcdwpc Posts: 159
    I'm a moderate driver. I don't leadfoot it, but neither do I lag traffic or baby the throttle. I'm getting 35-37 MPG on So Cal freeways and around 30 running to the mall and local driving. On long trips at 70-75 mph, I can get the avg close to 40. For anything more, I'd have to change my pretty normal driving habits radically. The only way I can get above 50 mpg for any period is to drive under 50 mph on a dead flat road. Even with cruise control, the slightest grade will cause the real-time mileage readout to plummet. Idling at stops lights has devastating effect on it. I can't drive that way. I know mileage will improve as the engine wears in over the first year, but its not 20%.

    Hypermilers show the economy potential for the TDI, but I think the way the TDI forums throw 50 mpg around is misleading and raises expectations of buyers unreasonably. The best thing about my JSW is that it get near or better than 40 mpg while giving sports car performance and pretty close to luxury sedan comfort.
  • asaasa Posts: 359
    edited July 2010
    I think one distinction with the '09+ TDIs that often gets lost in MPG discussions is that the car delivers excellent fuel ecomomy even with spirited driving. Other cars require driver compulsivity to achieve high fuel economy, but a driver can put the spurs to the new TDIs (with 140 HP and 236 LB/FT) and still be pleased at the pump. That's a rare and welcome combination.

    My wife and I are most ofen conservative drivers and our new (4000 Miles) '10 JSW 6M delivers 30 to 32 MPG in city driving and 43 to 47 MPG on the Interstate at 70 MPH. We are very pleased at the economy, appearance and sportiness of the car.
  • m6userm6user Posts: 2,897
    Uh, I thought I pretty much explained that this was a challenge to a bunch of auto writers to see who could get the best mpg over a certain course. Yeah, most of them went about about 30--35 mph. That's why I said nobody drives like that, it doesn't mean a whole hell of a lot but it's kind of interesting.

    Did my post sound like I was trying to say the Sonata gets that kind of MPG on average or something? I think it was pretty clear that I was not. I was just responding to the post about the couple that takes a TDI across country and got about double the EPA avg. 99% of people don't drive like that either. I was just trying to point out that by using all those tricks there are other cars out there capable of hitting some big mpg numbers besides the TDI if driven really, really conservatively.

    And yes, the TDI would probably still beat any car out there on an average mpg basis if driven correctly but just not by as much as some people would like to think.
  • bpeeblesbpeebles Posts: 4,081
    Mr Shiftright.... "coasting" actually REDUCES MPG.... let me try to explain it to you.

    First, you need to understand that all modern fuel-injected engines actually CUT OFF the injection of fuel anytime the engine is in overrun.

    Knowing this...If you were to go down a long hill (several miles)

    1) Allowing the engine to idle (coasting)...then the engine would be consuming fuel keeping itself idling

    2) Same hill, leave engine in high gear - foot off throttle, The engine-computer will cut all fuel-injection thus consuming NO FUEL AT ALL!

    Having an understanding of how the fuel-injection works helps alot. Hence, I keep my engine in gear AS LONG AS POSSIBLE as I approach a stop... pressing the clutch at the very last moment. This consumes the least amount of fuel.

    --------------------
    Also, you seem to use the term "hypermilers" in a derogatory way. Instead, I feel the techniques should be taught in driving schools. Many of the techniques which increase MPG also add SAFETY... Like always looking forward to anticipate a stop and get off the throttle early.

    I keep 40 PSI in my tires and short-shift as much as possible, think-thru my route to minimize road-time. (in your nomenclature - "Pick my routes")

    I do not consider this "hyper mile" driving. Instead, I have trained myself to drive as efficently as possible. It is second-nature to me (and my wife...since she drives the TDI more than I do so I cannot take credit for the high MPG)
  • MrShift@EdmundsMrShift@Edmunds Posts: 43,664
    Actually coasting probably does increase mileage because most people don't leave a car in gear without touching the gas going down slight grades---you'd slow down too much for the traffic behind you, so probably in the 'real world' the choice is between coasting vs. light pedal pressure in gear. You can go faster coasting downhill than you can by staying in gear with no gas pedal.

    I don't regard "hypermilers" as a derogatory term, but rather as an experimental exercise that isn't very practical in the real world. I often play with this myself just to "see how much I can get".

    Sounds like you are referring to common sense driving, which I'm totally in agreement with.
  • MrShift@EdmundsMrShift@Edmunds Posts: 43,664
    edited July 2010
    Your theory is right, but actually, in real life, coasting probably does increase mileage because most people don't leave a car in gear without touching the gas going down slight grades---you'd slow down too much for the traffic behind you, so probably in the 'real world' the choice is between coasting vs. light pedal pressure in gear. You can go faster coasting downhill than you can by staying in gear with no gas pedal.

    I don't regard "hypermilers" as a derogatory term, but rather as an experimental exercise that isn't very practical in the real world. I often play with this myself just to "see how much I can get".

    Sounds like you are referring to common sense driving, which I'm totally in agreement with.
  • ggeeooggeeoo Posts: 94
    You are so right what a difference at 60 years old I have owned many cars this VW
    TDI Sportswagon is great. Tight parking space no problem even when the guy behind
    you left six inches to spare. MPG 50 easily 3/4 of a tank from Newport Beach CA to
    Phoenix AZ. AC cold and forceful back and front seats.
  • asaasa Posts: 359
    edited July 2010
    Tight parking space no problem even when the guy behind you left six inches to spare.

    When we shopped for our new car, I carefully studied cargo capacity and exterior dimensions because we too dislike large vehicles. I was amazed at the number of SUVs and crossovers that are significantly larger in exterior dimension than the Jetta Sportwagen, yet offered significantly less cargo space behind the rear seat! In my analysis, it seemed that only Subaru and Volkswagen knew how to design an efficient interior and not bloat the exterior.
  • cosmocosmo Posts: 203
    Check your state laws. In most states, coasting out of gear is illegal because the driver is not in full control of the vehicle. If coasting was legal, safe, and increased fuel mileage, don't you think the manufacturers would have re-introduced the freewheeling overdrives of the 50's and early 60's? Maybe you should research Car Talk and learn what the real experts, the Tappet Brothers, think of coasting. ;)
  • MrShift@EdmundsMrShift@Edmunds Posts: 43,664
    I would hardly call the Tappet Brothers "experts" at much besides laughing at their own jokes :P

    All I said was that you can coast faster downhill in neutral than you can coast in gear with no gas applied----this is undoubtedly true, but I'm not RECOMMENDING it for gosh sakes! :shades:

    If you're like me, you don't have time to play hypermiler games. I need to get where I'm going, to drive "normally" like I always do, and hopefully, to get the best possible MPG while doing it.
  • bpeeblesbpeebles Posts: 4,081
    edited July 2010
    Have you even driven a diesel engine? ..... Since there is no throttle-plate, there is extremely little decelleration when foot is off the throttle. (almost none at all) A diesel engine is always allowed to breathe as much air as it wants.... hence, the only decelleration forces are the friction of the bearings, cams against the valvesprings, and rings scraping the cylinder-walls.

    With a diesel engine, it is very easy to have the engine in 'overrun' while going down a long hill. This is one of the many reasons that a diesel engine is inherently efficent.

    Contrary to what some folks will tell you, it is NOT the compression-ratio of an engine which causes decelleration forces. Technically, the force it takes to compress during piston upstroke is nearly identical to the force returned when the piston is on the downstroke. This cancells out the compression-ratio altogether. (Newtons laws in action)

    Instead, It is mostly the closed throttle-plate causing engine to pull a very high vacuum against it. (Gasoline engine has this inherent defect which reduces MPG)
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