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Best practices for high MPG highway driving, using "Torque"?

Discussion in 'Gen 3 Prius Fuel Economy' started by Jerry Liebler, Feb 24, 2014.

  1. Jerry Liebler

    Jerry Liebler Member

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    I've read a bit about "super highway" "sweet spots" but the articles used "scanguage" while I have "Torque". Where I live hills are everywhere and flat and level is very rare. Also I have no complaints whatsoever on my mileage, I just want to get all I can. When should I drive to maintain a constant ICE power output? What output? When should I look at ignition advance? what value do I want to maintain?
     
    #1 Jerry Liebler, Feb 24, 2014
  2. Easy Rider

    Easy Rider Active Member

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    Are you really going to enjoy "tinkering" with things in an attempt to squeeze out the last drop ??
    If so, forge ahead with the replies you are likely to get about various things that others will suggest.

    I think that it generally works out to be an exercise in futility, however, which borders on OCD.

    Keep the tires up at least to recommended pressure, drive slower if practical and use the cruise control to let the engineering built into the car do what it is designed to do.
     
    #2 Easy Rider, Feb 25, 2014
  3. CaliforniaBear

    CaliforniaBear Clearwater Blue Metallic

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    Your hilly area is very advantageous for the PiP. By switching into EV on down hill of any significant length you can build up the SOC (state of charge) of the battery for use in the flat areas. Be sure to switch to HV when going up hill as the ICE, with whatever electric power the car decides to use, is much more energy efficient than EV alone.

    For long flat areas cruise control makes for an enjoyable ride as recommended in the previous post. Be aware that mpg is directly related to speed. Also wind direction and road smoothness have an effect. If you're not in a hurry 55 mph is nice, probably around 60 to 65 mpg. At 70 mph you're probably closer to 5o mpg or maybe a little less.
     
    #3 CaliforniaBear, Feb 25, 2014
  4. Easy Rider

    Easy Rider Active Member

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    What ? How do you figure that ??
    It certainly would be a surprise to a lot of people.......since EV alone burns ZERO gas.
     
    #4 Easy Rider, Feb 25, 2014
  5. CaliforniaBear

    CaliforniaBear Clearwater Blue Metallic

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    EV does use energy, 1 gallon of gas equals 33.7 kWh. Going up a significant hill I lose about 3 EV miles per actual mile. Using gas (and whatever electricity the car wants) for uphill and EV in favorable terrain seems to give the best mileage over a trip with varying terrain. I'm sure that most folks driving the PiP will confirm this experience.
     
    #5 CaliforniaBear, Feb 25, 2014
  6. HaroldW

    HaroldW Active Member

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    Hills will drop you out of the super atkins mode. When I had my HCH2 sham was from 30 and 37 Degrees.. If you could keep it in that range you got great fe. I am not sure where this is with a Prius. H
     
    #6 HaroldW, Feb 25, 2014
  7. Jerry Liebler

    Jerry Liebler Member

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    Since I started this thread I've read several interesting web posts on how to drive a Prius to achieve best fuel economy at highway speeds. The conclusion I draw is, the goal is: to either have the ICE in it's best FE operating range (13 to 40 hp) or using no fuel (glide/coast). The high efficiency region is shown on the HSI as the right third of the wide bar and ends where the narrow PWR bar begins. If the terrain is 'flat' enough that cruise control operates in this range I won't be able to do better. However if I'm approaching an uphill I should use some pedal to speed up slightly before the hill so that climbing the hill will not get out of the desired operating range. If the hill is long enough or steep enough, I'll need to turn cruise off and use the pedal to keep the bar just below the PWR region until speed starts to build on the downhill side. As speed builds on downhills the instant MPG will jump up, when it hits about 75 MPG, it's again time to turn off cruise and go to "glide" (with a blank HSI bar) with possible regenerative braking if speed builds too far . The magic Toyota created in the CVT and control computers keeps the ICE at peak, constant, efficiency through a nice wide range of power output. "Torque" or other added instrumentation is really not needed, the HSI tells plenty. I'll still use "Torque" but mostly to monitor coolant temp as I'm running with grill blocking. It's also worth mentioning that the HSI is an excellent tool to monitor acceleration from stops, straying into the PWR region WASTES fuel.
    Well that's my 'strategy' along with 42/40PSI and using E0 gas whenever I can find it.
     
    #7 Jerry Liebler, Feb 26, 2014
    rexington, HaroldW and mtbiker53 like this.
  8. CaliforniaBear

    CaliforniaBear Clearwater Blue Metallic

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    If you are not in a hurry you might find using regenerative braking downhill to keep below 62 mph, where the ICE turns off, to provide better overall mileage. Above 62 mph the ICE is on in the compression mode (no gas) to limit the rpm of the motor. Those extra EV miles are quite valuable on the flatland.
     
    #8 CaliforniaBear, Feb 26, 2014
    HaroldW likes this.
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