Why is winter *highway* mpg so low?

[commadorebob]

This might be a hybrid only thing. Off the top of my head:

1. Batteries are known to struggle in the cold, so they don't hold as much charge, which will reduce MPG for Hybrids since the engine has to run more.
2. Heaters are not energy efficient. Same with heated seats and steering wheels, which will consume power requiring the engine to run more which offsets the benefit of the hybrid.

That said, I have an EB. I don't buy gas but once a month and my calculated MPG ten days ago was almost exactly what it was when I bought gas in August (actually 7/100th of a MPG better this last fill). So, I'm not seeing any difference.

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[npaladin2000]

Colder weather brings down MPGs, for many many reasons already detailed here. But I didn't see snow-tires mentioned (admittedly I skimmed). Snow tires are grippier than all-season tires, and that means more rolling resistance to overcome. But between that, cold air, winter blend gas, additional heat requirements, and all the rest, the efficiency deck is stacked against you in the winter.

 

[MikeS1942]

For the fourth time.... "heating" does not drain the battery.... and like OP stated, once up to highway speed, there is waste heat available. At least in positive F number temperatures there is.

Short answer: a bunch of little factors mentioned are all working against MPG.

Didn't say heating drains the battery, but all those other things like heated seat ,steering wheel radio and fans does drain the battery, so you are driving in hybrid instead of electric.

 

[Dave392]

On the highway??????

On the highway @70mph in winter I am getting 31mpg…..normally in warmer months I get 35-36mpg same trip, same speed (I know, I’m boring).

 

[hellokitty1984]

I have a '23 hybrid, and drive a normal highway route of 180 miles @ 70-75 mpg. My average speed is around 74.

Did it today, first time in cold temps (28°F weather) and got 27 mpg. Normal is 35-36 over the summer months. Keep in mind tire pressure was ~40 on all four (just filled them prior to trip).

Curious why low temps effect the hybrid mpg so much? Heat being on shouldn't bring it down from where it is in the summer, as the engine is running 100% of the time at ~75 mph.

Battery.

 

[MavMeister25]

On the highway @70mph in winter I am getting 31mpg…..normally in warmer months I get 35-36mpg same trip, same speed (I know, I’m boring).

Thanks for the info. I’m making mental notes of everyone’s feedback.

 

[Optimus]

Colder weather brings down MPGs, for many many reasons already detailed here. But I didn't see snow-tires mentioned (admittedly I skimmed). Snow tires are grippier than all-season tires, and that means more rolling resistance to overcome. But between that, cold air, winter blend gas, additional heat requirements, and all the rest, the efficiency deck is stacked against you in the winter.

You are very much correct about the effect of snow tires. In my post above, I’m describing an over 30% drop in MPG for me. A good 10% of that is snow tires. They are VERY soft and sticky, and therefore have a higher rolling resistance.

 

[MavMeister25]

You are very much correct about the effect of snow tires. In my post above, I’m describing an over 30% drop in MPG for me. A good 10% of that is snow tires. They are VERY soft and sticky, and therefore have a higher rolling resistance.

I can appreciate that. I do a lot of mountain biking and I upgraded my standard hybrid tires to mostly high-grip, sand/mud tires. They’re great in the trails. But on the road they are exhausting to have since they just do NOT coast. They just stop rolling like the brakes are on. Makes for a better workout

 

[TheQuixotic1]

Isn't the engine running 100% of the time at 75 mph? I use almost zero electric miles on my 75 mph 180 mile highway drives. I set cruise control to 75 and it just cruises.

I'm comparing summer 75 mph, 180 miles to winter 75 mph, 180 mile drive here. Summer is 35-36 and winter is 26-27.

Just crazy it impacts it that much. That's a 25%-30% drop in fuel efficiency for the same route, same speed, just different temperature. I've not seen that in our Prius.

Found this chart on a Canadian government website, most vehicles show a 7%-12% decline in efficiency:

Excellent post. I appreciate when people use specifics and clarify terms instead of throwing out generalities.

The chart paints the picture clearly: the two most fuel efficient vehicles on the chart (Accord L4 and Civic) both show a 20%+ drop in efficiency.

A full-size V8 truck is always going to be fuel inefficient, but that just allows it more wiggle room in sub-optimal conditions. The Accord V6 in the chart helps illustrate that point: it only loses 10% because it is an inefficient engine for that vehicle to begin with.

While you think your Prius might not be impacted, it ABSOLUTELY is significantly less fuel efficient in winter weather. You just might not have been attuned to it as much. Or, you also said you went through a prolonged colder than normal weather period; if you didn't have your Prius operate in similar conditions you can't exclude the possibility it would have very similar results to your Maverick.

A simple Google search reveals Prius drivers suffering from massive loss in efficiency because of winter weather:

Again: the more efficient the vehicle, the more noticeable the loss of efficiency will be; partly because you are more attuned to it being efficient and partly because it is operating outside of ideal efficiency conditions.

All vehicles suffer in cold weather.

ALL. VEHICLES.

 

[Matso]

Making me dizzy here folks with all the physics. My mileage does not change no matter the temperature, the humidity, barometric pressure or planet alignment. Seriously, my '24 hybrid maintains a relatively stable 38 mpg no matter the conditions. I have also found that the various driving modes make no difference in mpg either. I just leave it at "normal" and go. Simple is good.

 

[MakinDoForNow]

I have a '23 hybrid, and drive a normal highway route of 180 miles @ 70-75 mpg. My average speed is around 74.

Did it today, first time in cold temps (28°F weather) and got 27 mpg. Normal is 35-36 over the summer months. Keep in mind tire pressure was ~40 on all four (just filled them prior to trip).

Curious why low temps effect the hybrid mpg so much? Heat being on shouldn't bring it down from where it is in the summer, as the engine is running 100% of the time at ~75 mph.

The hybrid battery has to be heated to about 72°F in winter will be part of it also. Additional electric in winter could require a higher rpm of ice also. Consider 70-75 mph wind chill BTU's to be replaced in winter but it will help the AC some in summer.

 

[wb5oxq]

I typically drive 70 oh the highway and get around 40 mpg summer, 35 winter. 23 Lariat Ecoboost AWD 4k Tow.

 

[RatherB.Fishin]

I'm getting about 25mpg down from 27mpg in the summer. Actually a little better since I put 89 octane in the tank

 

[homerdog]

mine is also down to about 23, wonder if some gas stations have different blends of gas?

Yes, there are summer blends and winter blends. I think the winter blend has more ethanol mixed in which will decrease your MPG. I'm sure there are other factors as well, but my winter mileage has always dropped on every car I've owned.

 

[Toy Truck]

I've found that my 23 hybrid gets better mileage on cold days if I use the block heater. When the block heater is used the gas engine doesn't need to run as much to produce heat. I also find that I get warm air out of the heater much quicker. Doesn't take very long before the temperature gauge moves.

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