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Is "Super Highway Mode" a myth?

Discussion in 'Gen 2 Prius Fuel Economy' started by Briankbl, Jul 29, 2013.

  1. Briankbl

    Briankbl Junior Member

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    Okay, I can get killer gas mileage at anything under 55mph. But on my daily commute, I have a good stretch of road that is 65. When trying to use SHM, my car decelerates too fast for this to be a feasible method of driving. In a lot of the instructions I've read, they state to let off of the gas pedal a certain amount and you can usually get between 60mpg and 70mpg. For me, in order to reach that, my car loses 1mph every 5-10 seconds or so. Before I know it, I'm accelerating back up to 65 from 50 lol. Any advice on SHM would be great, thanks!

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    #1 Briankbl, Jul 29, 2013
  2. fuzzy1

    fuzzy1 Senior Member

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    My memory of Wayne Gerdes' description (at CleanMPG.com) is that SHM really ought to be practiced with an engine monitor (e.g. ScanGauge-II or similar device) to get the correct IGN and TPS values. And it is very unlikely to work at 65 mph.
     
    #2 fuzzy1, Jul 29, 2013
  3. Sabby

    Sabby Active Member

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    I have a Scanguage and use it at ignition at 22 to get SHM when going down hill or on a flat road. On the HSI it corresponds to just over the centerline. Pick that point and let there be a slow deceleration. MPG will pop up to the 75 plus area. Hope that helps.

    It does work best below 60 mph
     
    #3 Sabby, Jul 29, 2013
  4. Briankbl

    Briankbl Junior Member

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    Oh, duh...there's my problem lol. 65 being the speed limit, I would feel like a jerk if I drove below 60 lol. If I'm going 65+, should I just go ahead and use cruise control?

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    #4 Briankbl, Jul 29, 2013
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  5. Briankbl

    Briankbl Junior Member

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    Scanguage II is $160 on Amazon right now :-( Really want one, but I'd rather just use that money on gas lol. One day...

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    #5 Briankbl, Jul 29, 2013
  6. ItsNotAboutTheMoney

    ItsNotAboutTheMoney EditProfOptInfoCustomUser Title

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    CleanMPG.com, Wayne Gerdes' website, has a ScanGauge group buy thread where you can get it for a bit less. If you are serious about stretching fuel economy the ScanGauge's xgauge gives you access to some settings other, cheaper gauges won't. If you use a smartphone there are apps that use USB-OBDII cables to act as a gauge and there may be apps that are programmable.

    You m8ght be interested in Hobbit's article suggesting that you're bettermoff with high-speed pulse and glide

    Sweet spot refinement

    (Disclosure: I am a mod at CleanMPG)
     
    #6 ItsNotAboutTheMoney, Jul 29, 2013
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  7. fuzzy1

    fuzzy1 Senior Member

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    Those are specific to GenIII. OP has a GenII, no HSI gauge, and should aim for a different IGN value.
    Or support the PriusChat shop, $159.95. Or support CleanMPG.com, $134.95. Or wait for the occasional Amazon deal of the day, something around $125.

    Or get the baby ScanGauge (just 2 display items, not the regular 4) for around $100.

    Or since you already have a smartphone, try one of the apps (Torq?) that just needs a Bluetooth OBDII dongle.
     
    #7 fuzzy1, Jul 29, 2013
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  8. vskid3

    vskid3 Active Member

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    I would like to add the Ultragauge to that list. Its $70 and does a great job (but can't read any of the Prius specific sensors). Would be better than the baby Scangauge (called the Scangauge-E), which costs more, only displays 2 gauges at a time, and still can't do xgauges.

    Torque on an Android phone/tablet is the most useful per dollar for a Prius. A cheap bluetooth scanner ($15) and the app ($5) are all you need if you already have an Android device. With the customs PIDs, you can see just about everything the car itself sees.
     
    #8 vskid3, Jul 29, 2013
  9. theshark

    theshark Member

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    SHM!?!

    Is this some sort of modification? I don't have a SHM option anywhere in my 07 Prius?
     
    #9 theshark, Jul 30, 2013
  10. Prius_Cub

    Prius_Cub Member

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    Yeah, you just have to adjust the nut behind the wheel. ;-)

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    #10 Prius_Cub, Jul 30, 2013
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  11. theshark

    theshark Member

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    Hardy Har Har!!
     
    #11 theshark, Jul 30, 2013
  12. Prius_Cub

    Prius_Cub Member

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    #12 Prius_Cub, Jul 30, 2013
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