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Winter Tips?

Discussion in 'Gen 3 Prius Fuel Economy' started by Sporin, Oct 24, 2012.

  1. Sporin

    Sporin Prius Noob

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    The cold weather has hit us here in Vermont and our per tank average has taken it's seasonal MPG hit, down about 3-4 mpg over the last few tanks and I haven't even put on the snow tires yet. (from the high 40's to the low 40's)

    I don't drive the car daily, my wife does, so I'm uncomfortable doing the grill blocking thing. Her regular commute is about 35 miles each way of very hilly, rural highway.

    Going into our 3rd winter with the car. I ran Hankook iPike snow tires the first 2 winters but am going to purchase a new set of Blizzaks or Xice's or something a bit less aggressive this year and move the not-very-worn-but-very-loud iPike's to our old Accord which thankfully has the same tire size.

    Any other tips for improving winter MPG?
     
    #1 Sporin, Oct 24, 2012
  2. ForestBeekeeper

    ForestBeekeeper Active Member

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    You said low 40s. In your region how cool does it get in January-February?

    If you have seen your MPG drop even though it is only mid-40s, do you expect to see further drop when it gets cold?

    How far into the negative Fs do you normally see? What is your MPG then?
     
    #2 ForestBeekeeper, Oct 24, 2012
  3. Sporin

    Sporin Prius Noob

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    We are already below freezing some mornings. :) The past 2 winters, I've seen a steady low-40's all winter. I think that is because our trips are always long so whether it's the cold mornings of October or the 24-hour deep chill of January, my MPG stays about the same (low 40's).

    So, based on the last 2 years worth of tracking, I don't expect the temperature related MPG drop to get much worse. Snow tires will potentially knock a point or 2 off though still I expect.

    Wildcard this year was that I replaced my worn OEM Yoko's with non-LLR All seasons a few months ago and that cost me 2 mpg on average. With that in mind, I may not get much of a drop off with a set of Blizzaks as I did going from the LLR Yokos to the very aggressive iPike's.

    Hope that makes sense.
     
    #3 Sporin, Oct 24, 2012
  4. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    I don't think you should be nervous about doing grill blocking. If you want to stay extremely safe just do the next level down from whatever Ken suggests in the first post of the grill blocking thread.
     
    #4 markabele, Oct 28, 2012
  5. Dark_matter_doesn't

    Dark_matter_doesn't Prius Tinkerer

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    You can totally block the lower grill for air temps below 50 deg F with pipe insulation segments, but leave the upper uncovered for the sake of the inverter heat exchanger. I've checked coolant temps with a OBD-II interface and an iPhone app.
     
    #5 Dark_matter_doesn't, Oct 28, 2012
  6. Mendel Leisk

    Mendel Leisk Senior Member

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    +1 on above. Just keep the blocking conservative.

    My wife is the main driver ; she's also aware of the grill block. I'll block one (of two) of the lower spaces with the foam tubing pipe insulation, as soon as temps start dipping below 10C. Then when it's getting near or below 0C I'll block the rest of the lower. Typically that will last for a while, then when temp's ease I'll pull that second one out. While it is possible at extreme lows to block 50% of the upper, I just never bother.

    I secure the tubing with easily removable velcro strips, so if there ever was an overheating issue tube removal is easy and tool-free. Following this regimen for two years I've never seen overheating, and am monitoring with ScanGauge.

    One thing I leave in year round is a bit of tube blocking between the engine bay lid and adjacent body:

    IMG_1336.jpg
     
    #6 Mendel Leisk, Oct 28, 2012
  7. Dark_matter_doesn't

    Dark_matter_doesn't Prius Tinkerer

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    Velcro strips? The pipe insulation stays in place without any help. After a season, it shrinks enough that it doesn't fit tight but still stays on. Split the stuff lengthwise to get two equal half-rounds, then with the cut plane vertical, stuff it back into the slots. Make it full width of the grill so the ends keep the middle from going too far in.
     
    #7 Dark_matter_doesn't, Oct 28, 2012
  8. Sporin

    Sporin Prius Noob

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    thanks guys, I may give that a try this year and see how it goes. Without a ScanGuage, what kind of warning is there for an over-heating situation?
     
    #8 Sporin, Oct 30, 2012
  9. markabele

    markabele owner of PiP, then Leaf, then Model 3

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    Stay on the conservative side of things and take them off if you are going to be doing any travelling over 60 mph for very long and you don't need a scanguage.
     
    #9 markabele, Oct 30, 2012
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