[sears1234]

I found my MPG dropped from 42 MPG to 37 MPG in winter time, and read a lot explanation of engines and gas theories.
But I finally figure out it's my interior temperature setting affect it so much.
Here is my theory:
I set temperature to 68F in summer without AC, and 74F in winter.
My wife set temperature back to 68F last month accidently, and I was so surprised to see the MPG back to 40 again. I kept setting to 68F, and so far the odometer readout is still 40MPG, I guess my CT will maintain in that level.
What's you guy's thought?

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[hdave]

Agreed.
I just turn off my climate control in the winter if the temperate outside is over 0C (32F) and I'm back to getting 5.2L/100km (45 MPG)

I found my MPG dropped from 42 MPG to 37 MPG in winter time, and read a lot explanation of engines and gas theories.
But I finally figure out it's my interior temperature setting affect it so much.
Here is my theory:
I set temperature to 68F in summer without AC, and 74F in winter.
My wife set temperature back to 68F last month accidently, and I was so surprised to see the MPG back to 40 again. I kept setting to 68F, and so far the odometer readout is still 40MPG, I guess my CT will maintain in that level.
What's you guy's thought?

​

 

[SPAZZ]

In the winter I ride with the front defroster on set to low fan and 68-70 degrees and I'm still getting around 43-46mpg. Heated seats are also running.

In the fall I was getting 47-48 consistently with nothing on, so there is still up to about 10% lost. I'm sure some of that is due to the battery needing to warm up and the engine running because of that.

 

[hdave]

In the winter I ride with the front defroster on set to low fan and 68-70 degrees and I'm still getting around 43-46mpg. Heated seats are also running.

In the fall I was getting 47-48 consistently with nothing on, so there is still up to about 10% lost. I'm sure some of that is due to the battery needing to warm up and the engine running because of that.

How has the winter been in Chicago this year?

 

[rehabmax]

I always thought the heater used engine heat to warm the cabin and was not as much of a draw as the A/C. Then again it takes more energy to bring temperature up from 32 degrees to 72 than down from 85 to 75. I keep the temp at 72 in the winter. My mileage does go down from 46-47 mpg in the summer to 42-44 mpg in the winter. I think (i am not a chemical engineer to this is just my theories) there are many factors. Different blends of gas for winter. Colder temperatures make the battery less effective. Volume differences in gas in winter and summer. I'm just happy to be out of my old car that got 20 mpg.

 

[hdave]

I always thought the heater used engine heat to warm the cabin and was not as much of a draw as the A/C. Then again it takes more energy to bring temperature up from 32 degrees to 72 than down from 85 to 75. I keep the temp at 72 in the winter. My mileage does go down from 46-47 mpg in the summer to 42-44 mpg in the winter. I think (i am not a chemical engineer to this is just my theories) there are many factors. Different blends of gas for winter. Colder temperatures make the battery less effective. Volume differences in gas in winter and summer. I'm just happy to be out of my old car that got 20 mpg.

Yes it uses the engine heat to bring up the temperature, but if the engine cools, it'll need to turn on again.
And I believe that the A/C compressor can be run off the hybrid battery with the engine off.

 

[M Cook]

sears1234...Where do you live? I am in Philadelphia, PA. and even in this mild winter I have experienced the same mpg decrease. I have had the CT since March 2011 and have always averaged 42.1 mpg, until this winter. I have averaged about 37 mpg this winter. I have run the front windshield defroster on high and have had the heat turned up frequently. I will try the temp settings as you advised and see what happens. Thanks, Mike

 

[jimmyc13]

I always thought the heater used engine heat to warm the cabin and was not as much of a draw as the A/C. Then again it takes more energy to bring temperature up from 32 degrees to 72 than down from 85 to 75. I keep the temp at 72 in the winter. My mileage does go down from 46-47 mpg in the summer to 42-44 mpg in the winter. I think (i am not a chemical engineer to this is just my theories) there are many factors. Different blends of gas for winter. Colder temperatures make the battery less effective. Volume differences in gas in winter and summer. I'm just happy to be out of my old car that got 20 mpg.

Agreed. I think it's a little bit of everything that causes the lower MPG's.

 

[M Cook]

Yesterday was unseasonably warm in Philadelphia, PA. I filled up and drove around the city (no highway). Lots of hills/declines and stop lights and was back up in the low 40mpgs. There seems to be an obvious link between ambient temperature and mpg. colder weather = decreased mpg