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Figuring out potential gas savings with a 2011 Prius

Discussion in 'Gen 3 Prius Main Forum' started by pjay, Jan 10, 2012.

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  1. pjay

    pjay New Member

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    Oh, OK, thanks, SageBrush. I just asked the dealer and was told it would be no problem; I would just have to avoid using cruise control and vary my speeds.
     
    #41 pjay, Jan 25, 2012
  2. SageBrush

    SageBrush Senior Member

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    I have heard that advice before to avoid CC in a brand new car, but I have never understood the rationale. Is one trying to vary the engine load, or keep it constant? CC varies engine load and rpm dramatically. In a Prius there is no transmission gears switching, so any break-in is only gear and piston rpm.

    In my new cars I avoid flooring the fuel pedal, or even revving to high rpm for the first week. I don't know if it is really necessary, but I figure it is cheap insurance.
     
    #42 SageBrush, Jan 25, 2012
  3. pjay

    pjay New Member

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    Interesting that you have heard that advice before, SageBrush. I have heard the advice to vary one's speed for the first 500 miles or so, but I have never been told to avoid using cruise control for however long (I asked in a follow-up e-mail for how many miles I should avoid using cruise control and haven't heard back yet).

    As far as the rationale goes, you've got me. I know nothing about how engines work. I thought cruise control kept the engine (and engine load and rpm) steady, though?

    Makes sense to avoid flooring it, which I would do only in extreme situations anyway (such as merging on a short ramp or to get out of the way of an emergency vehicle). I don't drive aggressively! :)
     
    #43 pjay, Jan 25, 2012
  4. SageBrush

    SageBrush Senior Member

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    CC keeps the car speed steady. If you go down a hill the engine will idle or turn off (in the case of Prius.) Go up a hill, and the CC will whip the engine to not lose speed.

    Maybe that is problem with CC ? Thrashing conventional new transmission gears ?

    The more I think about this, the less I would be worried in a Prius with a reasonable driver holding the wheel. Good luck with your purchase !

    BTW, you can improve highway fuel economy by driving without CC in hilly terrain. I live in the low Rockies. I try to pick a rpm that matches my desired average speed and net elevation gain and keep my foot fairly constant. The car speed increases on downhills and decreases on uphills. I try not to speed over 75 mph, or less than 60 mph*. This works out to about 60 mpg at 65 mph average-- due to mile+ high elevation driving, perhaps 5 mpg better than lowlanders like yourself might achieve ;)

    * I usually have my lane to myself, or at least hundreds of yards between cars. Heavier traffic of course would not allow this kind of driving.
     
    #44 SageBrush, Jan 25, 2012
  5. pjay

    pjay New Member

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    Two
    Thanks for the luck wishes!

    Ah, OK, re: what cruise control does. Thanks. Yeah, maybe that is the concern--thrashing the gears when they're new.

    The dealer wrote back and said I shouldn't use cruise control for the first 1,000 miles, which would be a good chunk of the 1,800-mile round trip for me.
     
    #45 pjay, Jan 25, 2012
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