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Cruise Control Boogie

Discussion in 'Gen 3 Prius Fuel Economy' started by billklug, Jun 18, 2009.

  1. billklug

    billklug Junior Member

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    OK - call me a geek, but I've been thinking outside of the box as to how to to get more MPG out of my new Gen 3. :typing:

    Already incresed tire pressure to 42/40 from the 34/34 that the dealer provided; disappointing improvement. :(

    During the first 1500 miles of driving the car (almost all freeway), I have been using the cruise control in Eco mode to maintain a constant speed and, presumably, better mileage. It took me a while, but I recognized that this might not be the best approach.

    My commute TO work is 80 miles from sea level to about 1,100 ft - mostly uphill. The ride home FROM work is 1,100 feet to sea level - mostly downhill. Keyword, mostly; there are, of course, many areas of incline and downgrade along my regular path to and from.
    Today, I began to do drive a little differently.

    Using cruise, I would maintain speed up a hill (and charge the battery in the process), but at the crest of the hill, I would dis-engage the cruise (pull the lever toward me) and coast down (100 mpg instentaneous for as long as possible). When the speedo indicates a two MPH drop in speed, I hit "resume" (push the cruise lever up).

    So far (80 miles using this approach; just on the way home), the improvement has been about 3 MPG from 52 to 55 - of course this is only a one-way result as I only started this on the way home tonite.

    Interested to see what tomorrow morning brings. Some improvment, none the less, and will advise as to on-going results.

    Jeesh!! Have I turned into a I a "hypermiler"?!? I still like the 75-80 MPH cruising speed, but if I can do that and get 55+ MPG, I'm in!

    Film at 11.
     
    #1 billklug, Jun 18, 2009
  2. a priori

    a priori Canonus Curiosus

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    You may end up doing even better if you accelerate more on the downslope (where the marginal cost of increased speed is very low) and allow the speed to die off a bit more on the upslope (then you'll be using less uphill acceleration and saving a lot of gasoline).

    Just a thought!
     
    #2 a priori, Jun 19, 2009
  3. billklug

    billklug Junior Member

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    Worth a try, indeed. Thanks for the thought!
     
    #3 billklug, Jun 20, 2009
  4. fred garvin

    fred garvin New Member

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    i don't think cc is good at all for high MPGs and i base this on my gen 1 2002.

    cc doesn't take advantage of inclines - it wants to maintain the set speed going up a hill, where i might if not using cc and conditions permitting want to let the speed dip a little (not pay the price of maintaining the speed). then on the decline, i might want to (as mentioned above) get some cheap speed. Analogous to a fighter pilot trading altitude for speed.
     
    #4 fred garvin, Jun 20, 2009
  5. tmanson

    tmanson Geetar-playin' Traveler

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    I think that both of these responses are good ones. Of course CC was not designed for fuel savings, and perhaps there is better type CC needed for this, one that gradually allows the vehicle to accelerate on downhills and slowly decelerates on inclines. CC has become characterized as a constant speed controller, but perhaps it shouldn't be for our purposes (it could still be a "cruise control" just not a constant-speed cruise control). In another thread I just read, I saw mention of an econo-mode CC (or something like that). I need to understand what that is and if it attempts to do what I just described (I doubt it).

    Tom
     
    #5 tmanson, Jun 22, 2009
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