Winter MPG Drop!

Discussion in 'Gen 2 Prius Fuel Economy' started by Shaboom1965, Feb 21, 2010.

  1. Shaboom1965

    Shaboom1965 New Member

    Joined:
    Feb 21, 2010
    1
    0
    0
    Location:
    Greensburg PA
    Vehicle:
    2008 Prius
    Model:
    N/A
    I'm new here so please forgive me if this matter has been covered in a prior thread.
    My wife loves her 2008 Prius, which she bought in the summer of '08 when we had to fight to get a brand new one. However, the next winter, her mileage fell from a typical combined 50 plus mpg to low 40's and then went back to the normal 50 plus mpg when the warm weather returned. This winter, it has done the same thing. Is this part of the Prius nature or are we doing something wrong? She drives the car reasonably and it is garage kept.
    Great car by the way. Not a single problem since delivery.
     
  2. paulccullen

    paulccullen New Member

    Joined:
    Nov 14, 2006
    276
    3
    0
    Location:
    Seattle, WA
    Vehicle:
    2005 Prius
    Yes, it's true, the MPG drops with cold weather (mine goes from around 50 in summer to the low 40s in winter). But this is true of any car, since an internal combustion engine is much less efficient when cold. You just notice it with the Prius because of the handy MPG display.

    Also, batteries are less efficient (have a higher internal resistance) when cold. But I suspect that the MPG effect of a cold NiMH HV Prius battery is pretty small compared to the MPG effect of a cold ICE.
     
  3. thelungmd

    thelungmd New Member

    Joined:
    Nov 1, 2009
    7
    0
    0
    Location:
    New Orleans, LA
    Vehicle:
    2008 Prius
    Model:
    N/A
    The air is also denser when cold, hence more drag = less MPG
     
  4. bc104

    bc104 Junior Member

    Joined:
    Mar 6, 2007
    57
    2
    0
    Location:
    New York
    Vehicle:
    2007 Prius
    I have insulation on the engine and the grill blocked. It does help a little. Keeping the heat off around town and turning it on when on the highway helps more. But man that's cold!
     
  5. cwerdna

    cwerdna Senior Member

    Joined:
    Sep 4, 2005
    12,544
    2,116
    1
    Location:
    SF Bay Area, CA
    Vehicle:
    2006 Prius
    Yep... an engine block heater will help too but it's not nearly as cheap as blocking the grille. As for only turning on the heat while on the highway, I turn it when I need to do harder acceleration or above 42 mph. At that point, the ICE must run anyway.
     
  6. JimboPalmer

    JimboPalmer Tsar of all the Rushers

    Joined:
    Apr 14, 2009
    12,300
    6,692
    2
    Location:
    Greenwood MS USA
    Vehicle:
    2012 Prius v wagon
    Model:
    Three
  7. fuzzy1

    fuzzy1 Senior Member

    Joined:
    Feb 26, 2009
    14,907
    8,330
    90
    Location:
    Western Washington
    Vehicle:
    2012 Prius
    Model:
    Three
    In the old days, all cars preferred the summer blend for fuel economy, because it had higher energy density. I haven't kept up with any recent changes.

    As for the higher air density on cold weather, that does more than just increase air drag. It also increases part-throttle engine pumping loss. But this has more impact on non-hybrid Otto cycle engines than the Atkinson cycle engines in most hybrids.
     
  8. richard schumacher

    richard schumacher shortbus driver

    Joined:
    Mar 27, 2004
    7,656
    1,009
    0
    Location:
    United States
    Vehicle:
    2004 Prius
    Model:
    N/A
    Absolutely normal. It's happening to every other car on the road, but even more so for them. There's no need to worry or do anything about it unless you want a new hobby :_>

    Well, you do need to check and maintain the tire pressures at least monthly.
     
  9. WishingStone

    WishingStone New Member

    Joined:
    Feb 24, 2010
    9
    0
    0
    Location:
    CT
    Vehicle:
    2009 Prius
    Model:
    II
    I notice a significant drop. During the summer I hit 69 mpg... 54 or so at the lowest.

    However in the winter I struggle keeping 46, and usually I get 45 or so when I get angry, turn off the screen, and stop paying attention. I try to avoid using heat in the car, which helps the mpg I get. Though, most people wouldn't do that. My normal destination is a horse barn where I am outside 24/7, so the cold doesn't phase me anymore.

    Its better than anything else though, so I can't complain.
     
  10. elcorazon

    elcorazon New Member

    Joined:
    Sep 4, 2007
    74
    0
    0
    Location:
    chicagoland
    Vehicle:
    2007 Prius
    I get 40-46 in the summer and 30-37 in winter. Sucks but it's the way it is. My Honda Odyssey only got 14 last tank. Gets 25 in the summer on the highway.

    I do think the winter difference is more dramatic in the Prius than in other cars I've owned, though.
     
  11. ItsNotAboutTheMoney

    ItsNotAboutTheMoney EditProfOptInfoCustomUser Title

    Joined:
    Jul 18, 2009
    2,287
    458
    0
    Location:
    Maine
    Vehicle:
    2010 Prius
    Model:
    II
    While's definitely worse than other cars, do remember that the drop in the Prius isn't quite as bad as it looks.

    50 to 40mpg is 0.02gpm to 0.025gpm.
    That's an extra 0.005gpm.

    33.33 to ~28.57mpg is 0.03gpm to 0035gpm.

    25 to 22.22mpg is 0.04gpm to 0.045gpm.

    Mpg is deceptive.
     
  12. john1701a

    john1701a Prius Guru

    Joined:
    Jan 6, 2004
    12,129
    4,838
    57
    Location:
    Minnesota
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    You can say that again!

    Traditional cars actually see a really big efficiency drop in SUMMER, consequently appearing to have less of a drop in the WINTER.

    So, it totally how you look at it. Most just accepted that without question, since there were no other choices available in the past.

    Overall though, it's the annual average that tells the real story. Prius shines when you see that big picture view.
    .
     
  13. enerjazz

    enerjazz Energy+Jazz=EnerJazz

    Joined:
    Feb 18, 2004
    255
    141
    4
    Location:
    Fairview, TX
    Vehicle:
    2007 Prius
    Model:
    III
    Show me the data . . . . . and here it is:
    [​IMG]
     
  14. F8L

    F8L Protecting Habitat & AG Lands

    Joined:
    Aug 14, 2006
    19,011
    4,066
    50
    Location:
    Grass Valley, CA.
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    I try to explain this to people all the time and it seems they just don't get it. All they see is a 10mpg drop and they freak out.
     
  15. CaliforniaPrius

    CaliforniaPrius Active Member

    Joined:
    Oct 29, 2012
    313
    199
    0
    Location:
    Alameda, California
    Vehicle:
    2017 Prius Prime
    Model:
    Prime Advanced
    What I really care is the $ I spend, not data behind.
     
  16. F8L

    F8L Protecting Habitat & AG Lands

    Joined:
    Aug 14, 2006
    19,011
    4,066
    50
    Location:
    Grass Valley, CA.
    Vehicle:
    Other Non-Hybrid
    Model:
    N/A
    If all you were to read is your gas receipts you would sleep easier. The rest of us mpg freaks have to use sleep aids. LOL
     
  17. Daves09prius

    Daves09prius Active Member

    Joined:
    Nov 20, 2010
    680
    159
    0
    Location:
    Gettysburg, PA
    Vehicle:
    2009 Prius
    Model:
    One
    Grille Blocking will help improve the MPG during cold weather. The foam in the grille helps keep the ICE warmer and at the optimal operating tempature.

    Welcome to Priuschat! and hey! your in PA too! (y)
     
Loading...