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Discussion Starter #1
Can someone explain why the gas mileage is so terrible in cold weather, does the Volt not have a heater core? When I need heat I run the car in Hold rather than normal. Last night it was close to 0 so I had the heat on. The MPGe was awful as expected, 59MPGe, but so was the gas mileage, 33MPG, even though it was all highway. I under stand why the MPGe is so bad, batteries don't do well in the cold and the electric heater draws almost as much current as the engine, but why was the gas mileage just as bad? I've been operating under the assumption that heat would be free when running the ICE because internal combustion engines produce vast amounts of heat. Does the Volt not harness that heat? Is it always using the electric heater or is thee another reason why the MPG is so low?
 

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I've observed the % power of the climate system and it appears that the electrical demand goes way down once the engine is warm. Don't know whether you have a gen 1 or 2, but 33mpg doesn't sound too bad for 1 degree F. Even a pure ICE car is going to get worse mileage in extreme cold...
 

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Just like going up a long mountain grade produces crappy mpg, focusing on "poor" mileage over such a small duration as compared to the cars' lifetime is looking at things in the wrong way. That lifetime (year around) number on the center display is what's important. In the meantime, put the car in hybrid mode, crank that heat, and be comfortable till spring.
 

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I agree that 33mpg isn't terribly bad in those driving conditions. The ICE does produce heat for the cabin once it reaches about 140*. There is a 3 way valve that opens to include the heater circuit into the engine coolant and will provide ICE generated heat. If you ever get a chance, take a look at your MPG when climbing a mountain. I was saddened to see mine average about 16-18mpg via both mygreenvolt and torque. Of course the engine runs incredibly hard in that instance, but once everything settles back down it goes to a more expected 38-44.

Keep in mind that when temps cool, air gets more dense and requires the addition of fuel to maintain a proper AFR which will decrease mileage as well.
 

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Check tire pressures too, they will lower with cold temps. What speed on the highway? I would expect 10 or 20% worse after it warms up vs mild temps.
 

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All cars get worse MPG in winter, it's just that you notice it more in cars that display the number.

Fuel economy tests show that, in short-trip city driving, a conventional gasoline car's gas mileage is about 12% lower at 20°F than it would be at 77°F. It can drop as much as 22% for very short trips (3 to 4 miles).
The effect on hybrids is worse. Their fuel economy can drop about 31% to 34% under these conditions.
- https://www.fueleconomy.gov/feg/coldweather.shtml

Cold weather affects your vehicle in more ways than you might expect:

  • Engine and transmission friction increases in cold temperatures due to cold engine oil and other drive-line fluids.
  • It takes longer for your engine to reach its most fuel-efficient temperature. This affects shorter trips more, since your car spends more of your trip at less-than-optimal temperatures.
  • Heated seats, window defrosters, and heater fans use additional power.
  • Warming up your vehicle before you start your trip lowers your fuel economy—idling gets 0 miles per gallon.
  • Colder air is denser, increasing aerodynamic drag on your vehicle, especially at highway speeds.
  • Tire pressure decreases in colder temperatures, increasing rolling resistance.
  • Winter tires increase rolling resistance even more.
  • Winter grades of gasoline can have about 2% less energy per gallon than summer blends.
  • Battery performance decreases in cold weather, making it harder for your alternator to keep your battery charged. This also affects the performance of the regenerative braking system on hybrids.
In severe winter weather, your mpg can drop even further.

  • Icy or snow-covered roads decrease your tires' grip on the road, wasting energy.
  • Safe driving speeds on slick roads can be much lower than normal, further reducing fuel economy, especially at speeds below 30 to 40 mph.
  • Using four-wheel drive uses more fuel.
 

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All cars get worse MPG in winter
EXACTLY.

My old Magnum that I replaced with my Volt got about 15L/100KM in the summer in mixed driving (15MPG) but would go right in the toilet (to about 12.7MPG) in the winter.

The same thing happens on the Volt when running in gas mode as the same laws of physics applies - cold weather and all the things that come with it can drastically effect economy in a negative way. Even in electric mode this holds true.
 

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All vehicles take a big hit in mpg's in winter. Hybrids seem to be more effected by it however. I have noticed that our 2016 Volt Premier takes less of a hit in mpg's on the gas engine than our 2010 Prius does in the winter.
 

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Discussion Starter #9
The roads were clean and mostly highway, my trip was 66 miles each way so there was plenty of time for the engine to warm up. I don't know about the tire pressure, I don't have sensors in my snow tires. Is everyone else seeing this kind of MPG in there Gen2 Volts in very cold weather?
 

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I don't know about the tire pressure, I don't have sensors in my snow tires. Is everyone else seeing this kind of MPG in there Gen2 Volts in very cold weather?
Tire pressure unknown? You should be checking your psi regularly if you are going to get fussy about MPG.
Also, snow tires can knock 5 MPG off the car. Then add the other negative affects of cold listed above.
 

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I don't have sensors in my snow tires. Is everyone else seeing this kind of MPG in there Gen2 Volts in very cold weather?
90% sure it is the added rolling resistance of your snow tires. The could easily take 15% off your efficiency (4 to 6 mpg). Added rolling resistance. Cold will impact it some too.
 

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Cold weather is a bummer for EV ownership at this point. When we start to see battery ranges of better than 300 miles in cold weather and fast charging times things will really take off. Just not there yet.
 

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Cold weather is a bummer for EV ownership at this point. When we start to see battery ranges of better than 300 miles in cold weather and fast charging times things will really take off. Just not there yet.
My Bolt can easily do 238 miles. The top range (based on driving style) is 299 miles. I have the DCFC option and have not used it, nor have I needed a public charge at 240V. The daily commute is 70 miles round trip (half highway, half city) with heat blasting in the winter. Always arrive home with lots of extra range. But for very long interstate trips, we'd take the Volt with it's unlimited range and very fast refueling.
 

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Weenie. :p

Check your mileage with the -25°F we had this last week.
 

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Just a quick "perspective check" here.

In the current temperatures (hovering in the 8-11 degree Fahrenheit range) with "winter gas", my Jeep Cherokee gets a combined average of 16mpg.

Yes, you read that right... SIXTEEN freaking miles per GALLON!

The absolute worst my Volt has ever registered under a "perfect storm" of bad weather conditions, out of battery, and short hops to do errands, was 29mpg and that was already climbing as the REX finally got warmed up.
 

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Not thad bad considering..

at -6 in the sun today in Lutsen, MN. (with ambient windchill at -25 with gusts upwards to 7 to 11mph)

Wife's Mitsubishi Lancer who usually would average 33 mpg in the summer is at 22.3 mpg (ScanGauge II) with Cooper A/S Grand touring.

My Silverado with AFM usual average of 17.4 mpg (DIC indicated) is at 11.7 mpg on OEM stock tires.

My Gen III Prius which lifetime is around 50ish (indicated) is currently hovering at 38-40 mpg running Defender A/S.

My 2012 Volt is showing 25 miles of range and averaging 33mpg @ -6F on Shell ethanol free E87 ;) also running Defenders A/S. The MPGCS in these conditions ranges from 19 to 20 mpg IMHO is pretty amazing considering our arctic holiday blast. I usually put Shell premium in once these types of conditions are over. I'm also running 0w30 Mobil 1.

Once the air temp goes back above freezing I'll be looking forward to pure electric again.
 

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Discussion Starter #19
Weenie. :p

Check your mileage with the -25°F we had this last week.
OK, so it could be worse. I went to college in Appleton, Wisconsin and it got down to -40 (-70 with the wind chill as if that matters at that temp), so I'm familiar with the concept of really cold weather. However I've been living in New England for the past 40 years and this is the coldest it's been here on New Years for 100 years.

So did you leave the house last week, how did your Volt do at -25?
 

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Just for the record, wind chill is a made up thing for humans. It doesn’t effect inanimate objects like cars and batteries. :)
 
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