By on January 10, 2014

2015 Volkswagen Passat BlueMotion 01

Another day, another early unveiling prior to the 2014 Detroit Auto Show, this time from Volkswagen AG with their 42-mpg Passat BlueMotion Concept.

The magic behind the concept’s fuel economy lies within its turbocharged 1.4-liter gasoline four-pot; at city speeds, the engine deactivates two cylinders to boost economy, a feature already found in the automaker’s Polo and Golf sold in Europe. Other fuel-saving methods include a stop-start system, and a coasting function that decouples the engine from the transmission when the driver lifts off the accelerator; the latter is already available in the Jetta Hybrid.

The above setup — which Volkswagen aims to evaluate for the U.S. market — improves upon the current base Passat’s 34 mpg highway from its 1.8-liter turbocharged power plant, though horsepower drops from 170 to 150. The Jetta may also receive a similar package in order to improve upon its 32 mpg highway rating in an effort to catch up to more efficient offerings from Honda, Hyundai and Mazda.

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22 Comments on “Volkswagen Passat BlueMotion Concept Unveiled Before Detroit Debut...”


  • avatar
    Halftruth

    I’ve always thought “true” coasting used less fuel though I have heard arguments against it. Must be something to it if they added a decoupler to this car. Lots of technology here, stop/start, cylinder deactivation and the decoupler. Hopefully all of this stuff is ironed out for (more or less) reliable operation over time.

    • 0 avatar
      LeMansteve

      Coasting in gear: Transmission is “coupled” to the engine. Fuel injectors shut off but you slow down due to engine braking and gearing.

      Coasting out of gear: There is no deceleration due to engine braking or gearing. I believe this is essentially what VW calls decoupling. Fuel injectors are on with engine at idle. Perhaps the transmission is prepared with the correct gear for when you step on the accelerator, but that is irrelevant since it is decoupled from the engine.

    • 0 avatar
      LeMansteve

      Amending my comment because I get an error when I try to edit it:

      I would assume decoupling uses less fuel if VW made the effort to develop the feature. IIRC, the newer S-class and/or 7-series also feature transmission decoupling.

      • 0 avatar
        th009

        With my car, it appears that in-gear coasting is more efficient. However, if the engine also shuts down two cylinders, out-of-gear coasting may be the better choice.

        • 0 avatar
          danio3834

          Coasting in the highest gear possible will usually result in better fuel economy as already noted, most cars nowadays will actually shut off fuel delivery under prolonged negative load conditions.

          Out of gear, the engine merely returns to idle.

    • 0 avatar
      ash78

      Depends on the hill you’re coasting down. If you’re accelerating downhill in neutral, it’s often better to stay coupled in top gear and allow the drivetrain to brake slightly. In most care, the injectors are off and mpg is infinite.

      Finding the right balance is key — on a shallower hill, true coasting is better because if you were in gear, some additional throttle would be needed to keep up your speed.

      Interesting that in my 5MT, coasting downhill is technically illegal, but if an auto tranny achieves the same task, it’s apparently ok.

    • 0 avatar
      suspekt

      Ultimate coasting:
      Using a Toyota Prius HSD system to operate in Phantom mode…. For Gen 2, this means:
      - any speed below 40mph +
      - manipulation of the gas padel can achieve a state where REGEN is disabled, engine is off, engine decoupled from wheels

      I have never encountered a car that can coast for the distances a Prius can… the combination of incredible coefficient of drag, skinny tires, true engine decoupling, no regen means registers incredibly low loss of speed over long distances….

      There are many unadvertised benefits to a hybrid drivetrain that are simply not possible in an automatic or manual transmission vehcile…

      and before people start throwing rocks at me for being a tree hugging Prius driver, my other car has an LS1 in it….. FWIW

  • avatar
    frozenman

    If the 1.8t is essentially the same engine as the 2.0 I would stick with that IMHO. Adding all this tech to a 1.4t and then wringing its neck trying to move this size/weight of possibly fully loaded family conveyance seems ‘iffy’ to me. Maybe I’m too old school?

    • 0 avatar
      frozenman

      On another note why can’t manufacturers build a 3.0 v6 with descent power/fuel efficiency for this class of vehicle? Then start adding in stop/start tech and cylinder deactivation for cruising. Some torque at low rpm’s would be nice.

      • 0 avatar
        ash78

        A great question. My ’98 Passat (2.8L V6) can do 29-30mpg on flat highway in good conditions, and it sits right around the torque peak at 75mph (~3k RPM). That makes for very good highway driveability, but I always thought a 6th gear would probably net a few more mpg pretty easily.

        I’m still a little skeptical about all the “small engine wringing” you described. A few extra mpg from a frenetic hamster engine isn’t always good when a large-displacement engine with the right gearing could do almost the same thing, and likely with better reliability and longevity.

      • 0 avatar
        sgeffe

        Honda Accord V6–80mph, mid-30s MPGs! Classic sleeper!

  • avatar
    wmba

    Interesting. Coasting in neutral and/or coasting with clutch disengaged is specifically prohibited in my province, and probably in many other jurisdictions. I just google checked – yup it’s illegal just about everywhere.

    Since as mentioned, modern cars have fuel injection cutoff when the driver removes foot from accelerator and “coasts”, thereby using no fuel, there appears to be a logical conundrum here with VW’s method which breaks our law by declutching the engine from the wheels. The engine must still be using fuel to run – by definition, this use is more than zero. If the engine stops, which seems likely, then it really is illegal except at vehicle standstill.

    This is either German engineering logic or some misunderstanding in translation,because it makes no sense. Plus, it’s illegal here. Did I mention that, Herr Doktor Piech Dipl Ing blah blah.?

    • 0 avatar
      th009

      I doubt that the car engaging the clutch would break your (BC?) law as written. I fully expect that the engine would still be running, albeit on only two cylinders.

      • 0 avatar
        ash78

        I’m sure there would be a loophole, but wmba is correct — coasting in neutral is illegal almost everywhere…but I guess that’s only if the driver elects it. I believe the theory being that you relinquish some control of your vehicle that way. But I stopped trying to understand traffic laws a long time ago.

    • 0 avatar
      claytori

      There is nothing in the Ontario HTA to prohibit this. I do this daily, with either MT and AT. As stated above, it depends on whether you are truly coasting, as on a near level surface, or riding downhill and need speed regulation and engine braking, as to which is more efficient. This technique requires concentration and isn’t dangerous if done properly. With the MT I occasionally go engine off on a long gentle downhill, then bump start when I need power. With AT this would be impracticable due to the absence of bump start. Yes, steering effort increases without PS, but at speed it isn’t that much and you get used to it. Power brake function is retained for several full stops without the engine running. If your jurisdiction doesn’t allow coasting downhill in neutral, then you can simply make very loooong shifts with the clutch depressed. Note that coasting in neutral on a level road will not be prohibited, allowing the standard hypermiling technique of “pulse and glide”.

  • avatar
    CoreyDL

    SO MANY SEAT TRIMS AND DECOR.

    I like it. I’m always a fan of piping. Not sure the VW crowd will appreciate that sort of thing though.

    And ditch the fake carbon fiber on the dash, there’s no place for that in a 1.4L Passat.

    • 0 avatar
      Kyree S. Williams

      That’s funny, because on another Volkswagen Group product, the Bentley Continental GT, the V8 model is the one that features more speed-suggestive cues and traditional sporting red Bentley emblems…rather than the W12 model. However, I’m also told that the V8 is the faster of the two, so there’s that.

  • avatar
    bill h.

    There were cars such as the Saab two-strokes from the 50s and 60s that had a “freewheeling” feature–the engine automatically would disengage from the drivetrain when the gas pedal was released, even while the engine continued to run at idle speed. This was absolutely necessary with the two strokes, because you didn’t want to have the engine running under load without the fuel, as it had the engine lubricant mixed in it. After the phaseout of the two-strokes, even some of the early model 4-stroke Saabs kept this feature for a few years, supposedly for fuel economy reasons.
    I’m not sure how this would have run afoul of any laws at the time, unless some provision was made for it as a design feature engineered into the car, rather than as a conscious action on the part of the driver.

    • 0 avatar
      cornellier

      The Rover P4 had that too, possibly other models. To save fuel, I think since they were four-stroke unlike the SAAB.

    • 0 avatar
      blowfish

      even the Audi 5000 turbo dsl fromt he 80s had a free wheel too.
      Soon as u off the gas the engine spin freely and the car basically can go as fast as she wants.
      I read free wheel were in US cars during the old days.

  • avatar
    Kyree S. Williams

    I really like the carbon fiber and piano-black trim as opposed to the cheap and overabundant wood veneer simulations that you get on nicer Passats. The new steering wheel also looks nice and closely resembles the one in the current Touareg. And the two-tone seats just accentuates the black dashboard very nicely. I do, however, wish that Volkswagen would finally offer projector-beam headlamps on its cars, because they just look nicer and every other mid-sized sedan—save for the Malibu LS—has them as standard equipment. 42 MPG is really quite good if Volkswagen is not planning to price this package out the wazoo. If they are, then…Accord Hybrid.

  • avatar
    VoGo

    Bluemotion is a confusing name for a gas engine. The industry has been trying to label diesel with ‘blue.’


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