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Thread: Tis the Season! (Crappy winter fuel economy)

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    Quote Originally Posted by Eggman View Post
    That article says there's about 2% less energy available in winter fuel, right? I don't think that accounts for the Mirage loss of fuel economy in cold weather.

    I can go about 4 weeks on a tank of gas. I notice increased fuel consumption in colder temperatures with the same tank of gas.

    No doubt winter gas is a factor, but there's more to that story.
    All vehicles I've owned get lower mpg during the winter months. I see no reason why the Mirage would be any different? I think winter blend gas is a large part of it all. Other factors are surely in play even if you don't change tires during the winter months. Obviously, driving through snow or slush isn't going to help one's rolling resistance.

    Early to mid-November is when I notice a change in my area, too. It may be a combination of different fuel & tires in my case.



  2. #12
    Moderator Eggman's Avatar
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    Take a look at my (or any other cold-climate) Fuel Economy Log entries that have been collecting data for several years. You'll quickly notice the summer to winter variations are much more than 2%.

    I've noticed a direct correlation between temperature and fuel economy - lower temperatures mean lower fuel economy numbers, even with the same gas in the tank. In my opinion, this suggests the Mirage ECU delivers more fuel in colder temperatures. There has been a recall to reprogram the Mirage ECU to deal with an excessively-rich fuel condition in cold temperatures.

    I don't fully understand why the air-fuel ratio needs more fuel in colder temperatures. Your article suggests that cold fuel isn't as volatile, and that makes sense. I'm thinking that in the case of the Mirage, Mitsubishi has ordered more fuel than is necessary.

    Forum member foama has shown us a way to combat this by fooling the ECU into thinking the engine is warmer, and in turn the ECU delivers less fuel. His fuel economy numbers improved with his modification. Just providing evidence to support my claim.



    Quote Originally Posted by Mark View Post
    All vehicles I've owned get lower mpg during the winter months. I see no reason why the Mirage would be any different?
    The manufacturer's programming. Mitsubishi has programmed the Mirage Engine Control Unit to deliver a richer air-fuel ratio for colder ambient temperature operation.

    Quote Originally Posted by Mark View Post
    I think winter blend gas is a large part of it all.
    I do not doubt it is a factor, but no more than 2% as your article claims.

    Quote Originally Posted by Mark View Post
    Obviously, driving through snow or slush isn't going to help one's rolling resistance.
    So far I've encountered rain and some slushy road conditions, but mostly wet roads. Again, it doesn't account for all the loss of fuel economy.

    Quote Originally Posted by Mark View Post
    Early to mid-November is when I notice a change in my area, too. It may be a combination of different fuel & tires in my case.
    Sure, there are lots of factors that contribute to this. But temperature is the biggest.
    Last edited by Eggman; 12-02-2019 at 09:17 AM.

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        click to view fuel log View my fuel log 2015 Mirage ES 1.2 manual: 49.8 mpg (US) ... 21.2 km/L ... 4.7 L/100 km ... 59.9 mpg (Imp)


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    Senior Member Fummins's Avatar
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    Everything I can think of needs more fuel when cold. Start something carbed without using the choke or primer?
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        click to view fuel log View my fuel log 2014 Mirage SE 1.2 automatic: 36.4 mpg (US) ... 15.5 km/L ... 6.5 L/100 km ... 43.7 mpg (Imp)


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    Senior Member Wallythacker's Avatar
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    Quote Originally Posted by Eggman View Post

    I don't fully understand why the air-fuel ratio needs more fuel in colder temperatures.

    The manufacturer's programming. Mitsubishi has programmed the Mirage Engine Control Unit to deliver a richer air-fuel ratio for colder ambient temperature operation.
    The normal air-fuel ratio is about 14.7-1 or close.

    Colder air is denser, with the density increasing as the temperature decreases. The engine still expects, and needs, the same air-fuel ratio to run properly.
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        click to view fuel log View my fuel log 2017 Mirage ES PLus 1.2 manual: 39.0 mpg (US) ... 16.6 km/L ... 6.0 L/100 km ... 46.8 mpg (Imp)


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    Administrator MetroMPG's Avatar
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    Lots of reasons!

    There are LOTS of factors that drag down winter fuel economy.

    The winter fuel blend is just one small contributor of many. As Eggman and others have said, the biggest factor is outside air temperature, because it hits multiple systems:

    1) Engine takes longer to warm up, so it's running rich for longer.
    2) Entire drivetrain takes longer to warm up, so lubricants are thicker with more drag (transaxle, bearings, heck even CV boots)
    3) Tire pressure drops as thermostat drops - have you topped them up?
    4) Tire rolling resistance increases regardless of whether you've maintained pressure.
    5) Rolling resistance increases dramatically on snowy or slushy roads.
    6) You're running higher electrical loads because it's darker (headlights) and colder (seat heaters, blower, window/mirror defrost)
    7) If you have AC, the compressor kicks in when you select front window defrost.
    8) Some people idle their cars to warm them up, adding multiple "0 MPG" / "Infinity L/100 km" events to each tank average.

    A big one:

    9) Aerodynamic drag increases as ambient temperature drops due to increasing air density. Aero resistance can be twice as high in the depths of winter as in the warmest summer weather. Once you pass around 25 mph / 40 km/h, aero drag is responsible for half your fuel burn. It only increases from there.

    10) Ski racks? They're aerodynamically brutal.

    There are probably other things I can't remember at the moment.

    http://www.metrompg.com/posts/winter-mpg.htm

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        click to view fuel log View my fuel log 2014 Mirage SE 1.2 manual: 56.0 mpg (US) ... 23.8 km/L ... 4.2 L/100 km ... 67.2 mpg (Imp)


  6. #16
    Administrator MetroMPG's Avatar
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    On the plus side?

    1) Hot chocolate / spiked cider!
    2) Snowboarding, skiing & skating
    3) Crystal clear skies to appreciate the stars & winter moon at its zenith
    5) Christmas goodies (favourite seasonal food/treats!)
    5) Lounging in front of a roaring fireplace
    6)... I'm struggling here... help me out

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE 1.2 manual: 56.0 mpg (US) ... 23.8 km/L ... 4.2 L/100 km ... 67.2 mpg (Imp)


  7. #17
    Senior Member Fummins's Avatar
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    I got nothing to add to that. I am still getting better than ever economy compared to my other turd pails though!


    Reasonably Priced Car
    Truck
    POS Nissan

        __________________________________________

        click to view fuel log View my fuel log 2014 Mirage SE 1.2 automatic: 36.4 mpg (US) ... 15.5 km/L ... 6.5 L/100 km ... 43.7 mpg (Imp)


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