Why mileage gets worse in winter

Discussion in 'Gen 3 Prius Fuel Economy' started by cwerdna, Oct 30, 2011.

  1. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,218
    4,898
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    Ethanol was turned into snake oil.

    Most people are unaware of the effort long ago, before the boom.

    It was a long-term project to find fuel from waste and fuel from local providers. It was efficient, renewable, and green, none of the proganda we deal with now.
     
  2. Aaron Vitolins

    Aaron Vitolins Senior Member

    Joined:
    Feb 28, 2014
    1,611
    1,132
    0
    Location:
    Franklin TN
    Vehicle:
    Other Hybrid
    Model:
    N/A
    Anyone tried this?
     

    Attached Files:

  3. StarCaller

    StarCaller Senior Member

    Joined:
    Feb 15, 2014
    1,135
    624
    0
    Location:
    Cedar Crest, NM, USA
    Vehicle:
    2014 Prius
    Model:
    Two
    pretty much the same thing as water wetter, slightly increases the heat transfer/
     
  4. CreigMac

    CreigMac Junior Member

    Joined:
    Aug 5, 2014
    18
    7
    0
    Location:
    Anchorage Alaska
    Vehicle:
    2010 Prius
    Model:
    IV
    Wouldn't it make the radiator transfer heat faster? All metal surfaces in contact with coolant would, can't see it helping heater efficiency. I'd save the $10 and buy 3 gals of gas with it.
     
  5. markabele

    markabele owner of PiP, then Leaf, then Model 3

    Joined:
    Mar 27, 2012
    5,084
    1,777
    1
    Location:
    Nebraska
    Vehicle:
    2018 Tesla Model 3
    Model:
    N/A
    I agree, you can heat the car for a long time on 3 gallons of gas.
     
  6. Corwyn

    Corwyn Energy Curmudgeon

    Joined:
    Mar 6, 2011
    2,171
    657
    23
    Location:
    Maine
    Vehicle:
    2007 Prius
    Model:
    II
    Seems unlikely that the thermal transfer could be improved much. One could decrease the warm-up time by reducing the specific heat of the radiator fluid. However, the specific heat of the radiator fluid is what allows it to do its job. Imagine if you will, replacing ALL the fluid in the radiator with air. It would definitely 'decrease warm-up time', at the cost of not preventing 'overheating', 'seizing', and 'brickifying'.
     
    Redpoint5 likes this.
  7. briank101

    briank101 Member

    Joined:
    Jun 9, 2012
    170
    68
    0
    Location:
    Western Chicagoland
    Vehicle:
    2010 Prius
    Model:
    II
    If you remember to change to a low specific heat fluid in the winter and a high specific heat fluid in the summer it may be beneficial. If the winter fluid was about half the summer's specific heat it may work, but then it would also take half the time to cool down, in a Prius you don't want it cooling down faster either in winter as the engine will come on sooner to provide heat, but if you're driving on the highway at higher speed this may not be an issue. Now if you could dynamically vary the amount of fluid that's heated that would be good, but I think the Prius may do that any way, by only opening the thermostat as needed allowing the hotter coolant in the water jacket to gradually move into the radiator when a threshold temp is reached. If the car heater is pulling away most of the heat then perhaps very little of the hot coolant actually travels through the front radiator...... if not, I think it's the way it should work for efficiency's sake.
     
  8. qdllc

    qdllc Senior Member

    Joined:
    Aug 25, 2013
    1,314
    381
    0
    Vehicle:
    2013 Prius
    Model:
    Two
    IIRC, regular ICE motors run the fluid to the heater core independent of the radiator. So even a traditional motor shouldn't let coolant flow to the radiator until it's too hot to retain in the motor's coolant jacket.
     
  9. PRIUS POWERS

    PRIUS POWERS New Member

    Joined:
    Jul 31, 2015
    11
    1
    0
    Location:
    California
    Vehicle:
    2015 Prius Plug-in
    Model:
    Plug-in Base
    That's true - they're separate and don't intercept
     
  10. RacoonP

    RacoonP New Member

    Joined:
    Oct 18, 2015
    4
    0
    0
    Location:
    Kirowograd
    Vehicle:
    2012 Prius c
    Model:
    Two
    of course because it's winter
     
  11. methuselah

    methuselah Junior Member

    Joined:
    Feb 5, 2013
    17
    9
    0
    Vehicle:
    2012 Prius
    Model:
    Four
    And when there's snow on the sides of the road, that melts when warm or sunny, making the roads slicker/wetter, too. And when sand/salt is spread, you've got more slippage to the tires. And if you've got snow tires on, like I put on in the winter, even more rolling resistance.

    On a side note, I usually get better highway mileage than officially listed, and lower city mileage than officially listed...it's like mine is reversed.
     
  12. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    94,705
    42,940
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    whats your typical highway speed?
     
  13. methuselah

    methuselah Junior Member

    Joined:
    Feb 5, 2013
    17
    9
    0
    Vehicle:
    2012 Prius
    Model:
    Four
    Varies...on long trips, about 65-70, sometimes 75. Locally, closer to 60.
     
  14. bisco

    bisco cookie crumbler

    Joined:
    May 11, 2005
    94,705
    42,940
    0
    Location:
    boston
    Vehicle:
    2012 Prius Plug-in
    Model:
    Plug-in Base
    can't beat that.(y)
     
  15. PriusSport

    PriusSport senior member

    Joined:
    May 20, 2008
    1,498
    88
    0
    Location:
    SE PA
    Vehicle:
    2013 Prius
    Model:
    Three
    I'd like to get this subject going again. Started it elsewhere but didn't see any responses.

    I have a '13 base Prius I bought in August from my dealer--a leased car. I previously had an '08 Prius 2 for 8 years.
    The '13 Prius had only 20K miles on it, and I got 55 mpg until Nov. 4th, when I brought it in for a service check.
    I had the tires rotated and pressures increased for the winter.

    In the first few days, I found my gas mileage dropping--finally to 46 mpg after a couple weeks.
    I checked my tire pressures, and found they were slightly lower up front (mid 30s) than in the back.
    I had wanted 39/37. The car did show a harder ride. I readjusted the tire pressures to 39/37,
    and found the ride returned to what it had been in Aug-Oct.

    Today, I brought the car into the dealer for service. The tech said mileage drops because of 1) winter gas, in pumps starting
    Nov 1st, and 2) having your heater on, which uses the engine, not the main battery (!) I had raised temp up to 72, from about 65 in summer. Never realized heater could use gas! Don't recall that effect in my '08.

    I said OK, I'll check it out and let you know.

    I reset temp down to 65 (then on LOW--which is <65). I did get 56 mpg going about 5 miles from dealer to shopping mall--mainly highway driving. That was encouraging.

    What is experience here? I didn't see this much of a mpg drop on climate change with my '08.
     
  16. ssdesigner

    ssdesigner Active Member

    Joined:
    Jul 14, 2016
    304
    241
    0
    Location:
    california
    Vehicle:
    2013 Aqua
    Model:
    Persona
    I've posted this in another thread, but I'll say it here again:

    I'm in Minnesota. I drive a Gen4. I park my car overnight in a 70 degree heated lot. When the temp OUTSIDE was 70 or above, the ICE didn't need to fire up for my 1/2 mile, 25MPH commute.

    With the heater OFF, and outside temp 50 degrees or lower, my Prius ICE fires up within 1 minute after pulling out of the 70 degree parking lot.
     
  17. wjtracy

    wjtracy Senior Member

    Joined:
    Sep 19, 2006
    11,060
    3,479
    1
    Location:
    Northern VA (NoVA)
    Vehicle:
    2006 Prius
    Reportedly the Gen2's had worse MPG when cold, an electronic thermistor hack was somewhat common DIY here. The Gen3's were better and they say Prius v was better yet, as far as warm up speed. I assume Gen4 is better. There is just a long list of reasons cold hurts: less batt power, thicker lubes, lighter gaso, higher rolling resistance on tires. But mainly your Gen2 recollection is surprising.

    One thing to keep in mind, Toyota takes 50-state approach, so we have to take whatever MPG hit California wants to give less emissions in the cold. Last I looked FORD etc have slightly different vehicles in CARB states, so non-CARB states might get better cold start MPG in a non-CARB hybrid.
     
  18. Coast Cruiser

    Coast Cruiser Senior Member

    Joined:
    Mar 12, 2016
    2,267
    2,564
    0
    Location:
    Pacific Coast Highway
    Vehicle:
    2016 Prius
    Model:
    Three
    This morning it was 55°. I don't consider that "cold" at all. But I guess my car does. :LOL: My engine fired up immediately when I hit the power button. (No HVAC was turned on.) It's been doing that for two or three weeks now, and my gas mileage has decreased by 7 to 10 MPG. But I'm still getting 52 to 55 mpg in the city... So no worries. I'm more than happy with that.

    (To Star Caller: can you please get a new avatar that doesn't scare the sh*t out of us??? :ROFLMAO: :eek:
     
  19. Mendel Leisk

    Mendel Leisk Sand Pounder

    Joined:
    Oct 17, 2010
    45,523
    32,498
    80
    Location:
    Greater Vancouver, British Columbia, Canada
    Vehicle:
    2010 Prius
    Model:
    Touring
    In addition: the car has programming controlling functions, and it relies on various sensors, one of which is ambient temperature. I'm sure, when the temperature drops: it changes the car's behaviours, maybe: raising idle speed, delaying engine shut-off, and others?

    @Coast Cruiser alluded to this: with temperature drop his 2016 is no longer starting in electric-only, starts the engine immediately.
     
  20. Got2bHam

    Got2bHam Member

    Joined:
    Dec 10, 2016
    155
    51
    0
    Location:
    Missouri
    Vehicle:
    2012 Prius c
    Model:
    Two
    It's hard to avoid an mpg dip during the winter but there are things we can do to minimize it. Block heaters and blocking the grill as some have mentioned minimize it. I've been parking the Prius in the garage so that helps the leaving home part but at work there isn't a way around it. Turning down the temperature in the car has helped considerably.
     
    Mendel Leisk likes this.
Loading...