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The winter mileage of the prius has surprised me. I knew that it would drop, but its fallen from its summer-time level of mid-50's (per the MFD) consistently to mid 40's when the temp fell into the 20's/30's/40's area, and now to 31.6 on the MFD during a tank where temps have been mostly int he single digits. The gas engine hasn't shut off at all, it seems, since the temp fell below the 20's.

Thats more than 40% from my summer average. The car seems to be in perfect running order. Is this much drop in mpg to be expected?
 

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An Engine Block heater on a timer will help tremendously. You didn't tell us much about your situation...is the car garaged? How long is your commute? Do you need to use the defroster? What speeds do you travel on your commute? How many and how frequent are the stops? How high do you run the heat? Do you let the car warm up before driving? How many miles have you driven to get the 31mpg number you quoted? Have you added air to the tires since the temp dropped to keep them at the optimum level? What are the road conditions (snowy, icy, dry, wet?). How much wind has there been? Is it hilly open roads or flat city roads?

With that information and anything else you can tell us we can probably better inform you as to whether the numbers you're seeing are reasonable. Without it it's completely impossible.
 

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You might try turning off the climate control system at stops. Otherwise the ICE will keep running to try and keep YOU warm. However when cruising, ICE will be running anyway, you'll just be utilizing the waste heat that would be thrown out anyway.
 

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Hummius said:
The winter mileage of the prius has surprised me. I knew that it would drop, but its fallen from its summer-time level of mid-50's (per the MFD) consistently to mid 40's when the temp fell into the 20's/30's/40's area, and now to 31.6 on the MFD during a tank where temps have been mostly int he single digits. The gas engine hasn't shut off at all, it seems, since the temp fell below the 20's.

Thats more than 40% from my summer average. The car seems to be in perfect running order. Is this much drop in mpg to be expected?
I tell people I get 50 in the summer and 40 in the winter. Getting 38 on this tank. Nasty cold this week!
 

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I had a pretty big drop from about 53 to 48 (that's about 10%) when the season changed. However, my current tank is almost 54. The change? I drove three longer-distance trips. The previous few tanks were mostly 8-15 mile jaunts.

So seasonal driving habits might be a factor for a lot of people?
 

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Frank06 said:
Won't the car also try to keep the exhaust system warm (SULEV stuff)?
After reading a post and seeing a graph of some work that some Japanese owners did tracking ICE temps in cold weather with the AC set variable to "max cold/AC off (ie vent)" vs setting at a temperture to warm the cabin that, despite driving at a constant speed, the ICE temp variability was much greater when the car was set to keep the cabin warm.

What I've been doing the last few days (been in the single digits to low 30s) is turn the AC to the lowest fan speed, AC and Auto off, and the temp to max cold for the initial 5-10 minute of my drive. ICE temp comes up more quickly and I'm maximizing efficiency. After 5-10 min I usually start feeling cold so I turn the AC to about 67-68 degrees...just enough that I'm not getting frigid outside air. If I'm in stop and go type traffic I'll also drop back to the max cold setting to help retain the ICE heat. So far it's been pretty effective. Last tank finished at 58.3 and I'm around 53 on this tank after a morning of shuttling the wife around town in heavy traffic where th ICE was rarely getting up to temp.

Note, I also have both upper and lower grills blocked and some insulation packed around the ICE...I'm carefully monitoring the CAN-View to make sure I'm not overheating.
 

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MtnTraveler said:
I had a pretty big drop from about 53 to 48 (that's about 10%) when the season changed. However, my current tank is almost 54. The change? I drove three longer-distance trips. The previous few tanks were mostly 8-15 mile jaunts.

So seasonal driving habits might be a factor for a lot of people?
This has been pretty much my experience these past few days. After going from 54 to 48 mpg over several days of just 5 - 8 mile trips, I took a longer trip (200 + miles) and I was right back up to 53 mpg. But I console myself with the fact that 48 mpg is still better than I'd get with any other vehicle.
 

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My summer milage is very different from my winter milage. On an extended trip from Rangely Maine to Portland, Maine I got an amazing MPG average of 61.
Now that the cold weather has hit, my around town average is 30.5. True my trips are usually under 10 minutes around town, but it doesn't seem any better MPG's than a small car would get. New Hampshire can get very cold and with the car housed outside, I don't expect I'll see good MPG's again until June.
 

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SteveNH said:
My summer milage is very different from my winter milage. On an extended trip from Rangely Maine to Portland, Maine I got an amazing MPG average of 61.
Now that the cold weather has hit, my around town average is 30.5. True my trips are usually under 10 minutes around town, but it doesn't seem any better MPG's than a small car would get. New Hampshire can get very cold and with the car housed outside, I don't expect I'll see good MPG's again until June.
That's what I get in the winter when I'm on vacation and just hopping around in town. Commuting to work is more a 20-25 minute drive which give the car time to warm up and do it's synergy thing.
 

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Toyota attempted to make a hybrid act as a normal car rather than a "gimmic."
You can't have your cake and eat it too. Making you really cool in the summer and nice and toasty in the winter will cost and it's a cheap price to pay for comfort. My suggestion. Just turn off the mfd and forget gas milage until April.
In my mind, this constant search for max milage is a pain in the posterior in the winter and summer. If it bothers you that much just pull the fuse for the complete AC system.
If you want to add another excuse, don't forget the government mandated switch over to winter mixtures added to the gas and 10% enthonal did not help, but now we are getting political.
 

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MtnTraveler said:
So seasonal driving habits might be a factor for a lot of people?
Definitely! I avg. 53.1 in spring/summer/fall and about 44.8 winter... with current tank sitting at 42.4 after last weeks drop in temps.
 

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(Surprising that no one has discussed these yet. Yes, Dr. Fusco asked about warming up but didn't state what is the correct thing to do...)

1. Don't sit with the car ON to "warm it up" before going anywhere. Just sitting there burning gas without moving equals 0 MPG. As with any car the fastest way to warm up a Prius is to drive it, gently for the first five minutes or so.

2. Check the air pressure in your tires whenever the average outside temp changes by more than 10 or 20 degrees, and at least once a month. Some of us keep the front/rear pressures at 42/40 PSI to improve fuel economy (but this also noticeably changes the ride and handling).
 

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Count me as someone pretty happy with the mileage of my 06. In the summer I got anywhere from 55 to 62 MPG. Now, in December, in below freezing conditions I'm getting around 48-50.

On a different topic I can't say how pleased I am with the way the car handles snowy roads even in the OEM tires... The Prius is on damn nice car.
 

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Where I live, the major change in winter mpg is on short trips. Your mpg is at its worse during the warm-up cycle, and in cold weather that cycle lasts a lot longer.

So, for instance, when we drove to Pueblo yesterday - 45 minutes each way - with temperatures in the 30s and 40s, our mpg was down about 10 percent from what it is with temperatures in the 60s. But today I ran some short hop errands for my mother, with about the same temperatures, and the mpg was down at least 20 percent (and probably more) from the same trips in warm weather.

Hyp, the ethanol issue isn't political - it's medical. Winter air pollution is much more dangerous than summer air pollution because of temperature inversions. A couple of decades ago, Denver used to just disappear in the winter smog. It doesn't any more. This may not matter to you because you can breath, but I watched my father slowly suffocate from emphysema and chronic congestive lung disorder. That experience left me very grateful for the current pollution restrictions. Emissions was a major reason I bought a Prius.
 

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I've never hit 50mpg on a tank, so I've become resigned to even worse winter mileage over the past two years. With cold weather, heat, and short jaunts, I don't even expect to get out of the mid 30's. Just driving the Prius with such ease and no problems so far, I'm not complaining.
 
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