Cold Weather Hurts Prius Mileage

Prius in WinterDoes cold weather hurt a Prius’ mileage? Yes, according to Minnesotan, Michael Wurzer.

He ONLY got 29 MPG on a recent trip at -13F.

All cars get worse mileage when it’s cold. Duh.

How does that compare to your car’s mileage at -13F? Does your car even start at that temperature?

So, yes, the Prius gets worse mileage in the cold, bringing it down to the mileage of a typical high-mileage car on a summer day.

Photo credit.

24 thoughts on “Cold Weather Hurts Prius Mileage”

  1. Cars don’t get lower mileage directly because it is cold outside. The engine doesn’t care and actually likes the cold air it is intaking as it is more dense and therefore richer in O2. On the other hand, the gasoline that you purchase has fewer btu’s in the winter due to spec changes that allow for butane blending in winter but not summer. Butane only has 4 carbons and therefore has less power. (similar to ethanol btu issues) Less power = lower gas mileage.

  2. we rented a car last weekend for my wife to drive on a vacation and it ended up being a prius. she drove it maybe 500 highway miles and based on how much gas we put in, it averaged in the high 30’s mpg. it was killer cold, obviously.

    tire pressure goes down a lot in the cold weather, which can have a big impact on mpg. people forget that sometimes.

  3. Butane, eh? Okay, so the engine is solid in the cold, but there is more to running a car than pushing the pistons.

    My car takes miles to loosen up the transmission and in today’s cold air my car was still not shifting smoothly at any time in my 18 mile commute. Heater is on high, the tires are cold, steering is stiff, etc. So while the engine is effective, but all the systems it is pushing are less efficient…so the engine will still work harder and gas mileage will decrease.

    Then, I have a 2005 Prius in my 3rd winter driving it and I guarantee you my mileage suffers in the cold, about 20% less. So much so, I began to wonder if it was programmed by Toyota to do so as a way to keep its battery stronger longer. But now I just think it is natural due to two major factors–
    1) the above transmission factor, aggravated by the fact a hybrid has a more complex transmission trying to blend battery/electric motor into the gas engine…and you can hear how hard it tries to shift in the cold; and
    2) batteries suck in the cold and this is universal to all batteries as they all suffer in cold temps; they give weaker power, discharge easier, and take more time to recharge.

    But…even in this cold, it still averages more than 35 mpg and thus still performs better than 99% of USA’s vehicles.

  4. I’d blame the Prius mileage on the battery. If your transmission isn’t shifting properly, then you might lose some mileage–but that is your transmissions fault, not the cold (my transmission works fine in the cold).

    Tires are a little flatter due to the cold==less efficient. I’ll give you that.
    However–heat is nearly free (fans use very little energy compared to an AC compressor). The rest of the car warms up in less than 1 mile so that isn’t to blame.

    I’d blame 85% on the Butane, 5% on low tires and 10% on your car not shifting properly.

  5. I’d say the 85-5-10 factors sound right for an automatic transmission nonhybrid vehicle, but for my anecdotal Prius experience, I’d roll out the factors like this–
    50% battery, 30% butane, 5% tires, 15% transmission

    The butane is a subtle factor, invisible to the feel of driving, only apparent via more frequent trips to the gas station, so it is hard to judge without some scientific measurement.

    But more obvious factors are the added strain on the gas engine because of how weak the battery is in the cold, it is almost impossible to go even a block solely on battery power; and then it is noticeable how hard the transmission works trying to blend the power sources effectively under even modest acceleration in extreme cold.

    The Prius driver doesn’t need an engineering study to hear and feel those two factors involved in the cold. It’s that obvious. Still, I have never been stranded or been distressed driving it, and wouldn’t trade it for any other mainstream USA vehicle today.

  6. Heat isn’t exactly free – in order for there to be heat the engine needs to be running. One of the tricks my Insight does (and I believe the Prius does) is that it will shut down the engine when the car comes to a stop. But, in the winter the car keeps the engine running even when I’m stopped so it is able to provide me with heat, shaving off a few MPGs.

  7. Yup, Prius does the same. Heat and headlights (both of which are used more in winter), air conditioning in summer (which I rarely use), and I suppose the CD/radio too all cry for some power, and I too have noticed the gas engine shutting off in winter less as a result. Probably a 5% factor unless most of your driving is on city streets.

  8. Butane haters!

    😉

    BTW, the ALAMN’s leased E85 vehicles have been firing up just fine in the sub-zero mornings. Hope to get the new flex-fuel Impalla this year — I see a lot on the road already.

  9. E85…oh yeah, and I hear one of the GOP proposals for reducing the national debt next term is to remove all the ag and big oil incentives hidden into ethanol production and thus pass along to the gas/ethanol guzzlers the costs involved in the full production price of ethanol…it’s not a tax, right?

  10. Okay, I’m still laughing at my last post, but don’t want The Deets to get linked by Powerline without my clarifying statement here–
    “My last posting above was full fabrication (we all know the GOP has no original thoughts involving ag or big oil and will perpetuate these subsidies until death do our country part).”

  11. E85 should start up just fine–it has a very high RVP (vapor pressure), meaning that it vaporizes very easily.

    Biodiesel on the other hand, clouds at a temp around 35 F–and cloud is bad when you are talking engines.

    Enough already–oh, and what tax incentives does big oil get with regards to ethanol? I’m pretty sure there are none…

  12. This chart makes perfectly good sense. For many of the reasons stated above such as more resistance, lower pressures, time to warm up the engine, etc. I do not own a Prius, but I have a 2008 VW GTI with the fuel readout just like a Prius. On days in the 20’s and low 30’s, I will average 29-30mpg on my trip to work. On days when the temperature is in the 50’s or 60’s, I will average between 34-36mpg. This is a huge difference (about 15%-20%). So it’s not just the effect on your prius.
    Also, the Canadian site makes sense because I notice the longer I run my car in cold weather and things loosen/warm up, the better mpg I get.
    Another factor to condsider is how bad E10 kills fuel mileage. Most fuels are made with up to 10% ethanol. Ethanol only has 2/3 the power of gas, so E10 can easily cost you 2-3 mpg in addition to the losses that winter fuel blends give.

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  14. My 2003 Prius has 125,000 mile on it and I’m going into the 3rd winter with the car (bought it used). My actual mileage is usually 2-3 mpg less than stated on the screen. I thought the first winter (two years ago) I got close to 45 mpg and up around 50 in the summer. Last winter I struggled to get 40 mpg. According to other Prius owners on this blog, I should be happy with 40. Now we’ll have to see how long the batteries hang in there with the 20,000 miles per year we put on the thing!

  15. I have a 2007 Prius and the average mpg in the summer is 50 and 44-46 in winter.If I’m not mistaken the heat is an electric heat not a engine coolant heat which would put more of a load on electrical system. I have noticed in order to get the best mileage you have to drive it like a little old lady and keep your foot out of it. I have 65,000 miles on it and its a great car.

    Does anyone leave their Prius outside in the -20 or-30 below weather, any problems going in the morning?

  16. Hi Joe–I have a 2005 Prius on my third winter. I believe my model does not have electric heat as it takes too long for warm air from the heater, thus I assumed it was engine heated. One of my winter complaints has been that since I’m riding on a moving battery, why didn’t they throw electric heat in for its instant warmth (I’d take instant heat over 2MPG today!).

    My summer mileage is over 50, but my winter mileage this winter has been drifting under 40…which might be the first signs of aging or just that this winter is deeper (colder and snowier) than the prior two. As for the old lady driving for max mileage, it is best to pulse the speed until reaching 29+ when you can try to lay lightly on the peddle and keep it on the battery. This works best in light traffic jams or on parkways (less stop signs), once at highway speeds, you are doomed to whatever hybrid mix comes out at your driving speed (pulsing is not a good option in our cruise control world).

    I park it outside, but don’t recall Mpls reaching -20F in the last 3 winters (yet, maybe tonight, eh?). But in my experience, anytime the temps are below 0F, the transmission is VERY sluggish and it takes a couple miles before it loosens up enough for highway speeds–it runs total engine when first moving and the engine is running fine, it is the transmission attempting to shift that is so labored.

    I too think it’s a great car and have no real complaints, and am looking for even smarter cars to be availabe for when this one is ready to retire.

  17. I have a 2008 Prius and in summer and fall we got around 47 mpg. The temp here avg’s around 32 degrees in winter. Our fuel consumption has gone down to 30 mpg with 28 being the worst. The Toyota dealer says this is normal with heat and defrost. We are sparing with them, also the daily commute is 5 miles roundtrip. Does anyone else’s fuel consumption increase by 50% in winter? I feel the EPA estimate is misleading if it was calculated with no heat or whatever for winter driving?

    Anyone else having this low mpg who lives in a cold climate. Also car is garaged so it is reasonably warm for startup. I love the car, but the fuel consumption seems wrong

  18. 09′ Prius. I got a repeatable 50-53mpg this summer back and forth to work (9m one way). Now that temps are falling I’m seeing 46-48 so far and it sounds like it might drop even more. I have noticed a significant increase in rolling resistance. Checked tires twice, all at 35 psig. I’ve seen this in my wrangler, winter=thick lubricants. I don’t get as much roll on the flats and downhill as I used to. Not sure if there’s any way to try a lower viscosity blend. I switched to a synthetic in the jeep trans and it helped. On a longer trip to the city and 50F this past weekend my mileage went back up over 50. I noticed on starting that after several seconds of battery only the engine is kicking in and staying on for a while, didn’t used to do this, heater is off, defrost is off, etc. Has anyone tried plugging one of those solar pannels into the 12 volt aux plug to charge the batteries while parked? Was wondering if this would work? Thanks. Ed H.

  19. We bought our 2007 Prius used in 2009. During the summer it averaged 47 mpg. Now in our first week of realy winter in Buffalo, it’s dropped to 36 mpg and may head even lower. The transmission is definately sluggish and I was going to haul it in for a tune up, but doesn’t sound like that’s needed. I’m going to confirm the tire pressure. Thanks for the good tips and info. I’m not so worried about the reduced mpg now.

  20. I bought a 2004 this past summer and got 48.6 average in all forms of driving (A/C btw is electric doesn’t run off the gas motor) however now that the temp is in the low 30’s I have dropped to 39 mpg. Best I can figure its due to the gas motor running more to produce heat for the cabin. Also batteries have sharply reduced efficiency when the weather is cold.

  21. It is the decline in battery power and capacity in a cold environment. Since the battery can contribute less in the cold, the gas engine must do more of the work, hence lower gas mileage. On a per cent basis, the Prius mileage will drop more in the winter than a conventional gas engine, because after the warmup period, the steady state operating temperature of a gas engine is almost independent of the surrounding air temperature, with the coolant flow under thermostatic control.

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