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Horrible drop in MPG with winter over 30% drop

('14-'18) 
26K views 62 replies 39 participants last post by  emg 
#1 ·
My 2014 Forester is now averaging 15 - 18 MPGs in cold weather (10-20 degrees) when it was averaging 25 - 27 MPG's during the summer and fall.
Is this considered normal, or should I be taking it to the dealership to have them look at it?
This car is garaged while at home and is driven to work and back around 6 miles each direction in city driving with very little traffic.
I notice that the RPM's are running much higher than before, around 2500 RPM's even after it is warmed up.
If this is considered normal (30% - 35% drop in MPG's is extremely high to me), then is there anything we can do to get better MPG's out of the car during the winter, maybe different gas???
 
#3 ·
Nothing will help the MPG in winter.

Check your tire pressures.
 
#5 ·
The major factor is it takes longer for the oil and other bits to come to operating temps. in the winter. This creates more friction and the motor has to work harder. Short trips make this even worse. Couple this with winter fuel (alcohol in the gas has less energy for the same volume) In 6 miles the car won't get to operating temps at all. Be sure to give it an Italian tune up once in a while. When you start the car it dumps a ton of moisture in the exhaust system, if you don't get it hot enough to dry it out, it will rot form the inside eventually.
 
#6 ·
Check the mass airflow sensor (MAF) sensor to see if it's dirty. But the combination of the "winter blend" gas, denser air, and the fact that you are only driving very short 6 mile distances means that you are pretty much out of "optimal efficiency" operating modes during most of your commute. You probably don't get to operating temp (I'm talking diff fluids/transmission/engine/etc) until you arrive at work. My car doesn't get to operating temp for 3 miles during my 15 mile commute when it's cold outside, and that's just the engine. Automatic transmissions take longer. Cat converters can take up to 8 miles to get to proper operating temp as well. Essentially, your commute is not long enough to get the car into it's maximum efficiency (and winter gas doesn't help either).
 
#8 ·
Mine has dropped from about 30mpg to around 26-27mpg this past week (country roads). Weather turned colder and I installed winter tires. I also am letting the car warm up a bit more before driving which will have an impact. As mentioned, a 6 mile commute doesn't really give the engine/transmission enough time to warm up. I don't think there is anything wrong with your car. Take her on a long date this weekend and see if things improve.
 
#9 ·
Mine has dropped from about 30mpg to around 26-27mpg this past week (country roads).
My mileage has taken a pretty good drop as well. I was averaging about 32-34mpg on my 30 mile interstate commute, but now it's more like 27-28mpg, and depending on the wind, sometimes even less.

Winter brings many factors into play....

There is the higher rolling resistance of winter tires, richer fuel mixture, increased wind resistance, and the increased drag of snow and ice on the car.
 
#10 ·
Normal. Summer average for me is 28.5 to 29 MPG. Winter 23.5 to 24 MPG doing the exact same driving.

It's not your air cleaner or anything else like that. Engine just uses more gas when it's cold. I presume it does run richer when cold, but even after it reaches normal operating temperature, the MPG are still low.

This engine just uses a lot more gas it cold weather compared to warm weather.

The Forester with the exception of the All Wheel Drive system, is not a winter vehicle. Uses a lot of gas in winter and '14 heater is not the best in the world with providing heat in the vehicle as attested by many.
 
#11 ·
My 2014 Forester is now averaging 15 - 18 MPGs in cold weather (10-20 degrees) when it was averaging 25 - 27 MPG's during the summer and fall.

This car is garaged while at home and is driven to work and back around 6 miles each direction in city driving with very little traffic.
Are you using a block heater? That puppy's engine will get up to operating temp a lot quicker if it starts off warm...
 
#14 ·
I have noticed my mileage drop as well with the winter fuel, using the same brand (BP) 87 octane. I guess the only things we can do is keep the oil level, air filter and tire pressure maintained as well as a light touch with the gas pedal as much as possible. I can say with 100% certainty the same mileage drop also happens with diesel fuel.
 
#15 ·
Winter inevitably will decrease your fuel economy, but to me, that is too much. In the summer I average around 28 mpg. In the winter, it gets down to below -22F (<-30 C) and I still get 21-23 mpg. My trips are usually a bit longer than yours but my vehicle is also an 05 and shouldn't be doing better than you 14. If you have a lead foot, that is a different matter. You said your car idles at 2500rpm even when it is warmed up? That shouldn't be. It takes mine about 3-4 minutes to drop idle speed down to 1500 rpm from 2500 rpm.

It might just be everything else people have mentioned about winter driving but to me, you are seeing too much of a decrease in mpg.
 
#17 ·
This car is garaged while at home and is driven to work and back around 6 miles each direction in city driving with very little traffic.

This is the key right here. 6 miles is nothing. Your vehicle never really reaches FULL normal operating temperature EVEN though it indicates it has.

If it doesn't cost you anything to have Subaru look at it, go for it, you never know, but I will bet they will tell you everything is fine and it's your driving habits. Not sure where you live if they use winter blend gas, that also will add to the decrease in MPG. The combination of short drives plus the winter blend gas will definitely decrease your MPG.
 
#18 ·
This is the key right here. 6 miles is nothing. Your vehicle never really reaches FULL normal operating temperature EVEN though it indicates it has.
Yep. Even though your coolant gauge reads "warm", your oil temp, transmission temp, drivetrain fluid temp are not yet "warm".

This change in fuel economy doesn't sound surprising to me. MAYBE it's running slightly more rich than it is supposed to do, or for slightly longer than it is supposed to run rich, but, it sounds pretty normal to me.
 
#21 ·
I suspect the 2000 RPM's may be a result of the CVT which is designed to keep the revs high until it is warmed up. Makes me wonder if CVT equipped Foresters will show a greater variation in mileage between short summer and winter commute conditions like yours than say the 4EAT.
I certainly see a big variation here: ~9l/100km commuting in the summer vs 10-12 now it's winter. Part of that is the engine warming up, but the other part, as you say, appears to be the CVT keeping revs high until it warms up. If I stop the car when it's warmed up and then drive another few km, the fuel consumption readout is back to around 9l/100km again.

And I did manage to get it up to 99.9l/100km when driving around the block in the snow yesterday :).
 
#20 ·
My mileage drops during the winter months as well, especially when I'm just doing my normal commute to work and back that is similar to yours at about 5 miles. Engine revs higher and transmission is much louder until everything is warmed up, which takes close to 10 miles. Seems to be normal as everyone mentions, so I'm not too worried about it.

I'm a little concerned with the transmission whine I have when cold though, which has gotten worse/louder as I've gotten higher up in miles. Was thinking maybe I need to change the CVT and or differential fluid. Car pulls to the right pretty bad too, even though alignment has been done and all is good with that. Also have a little chirp noise at lower RPM's stopping and starting that sounds like the torque converter. Not sure if that is normal, but maybe that is related. From what I've read in the manual and heard, sounds like the CVT fluid shouldn't really need to be messed with until like 100k miles.
 
#22 ·
I too have been getting relatively terrible mileage on my 15 XT since the colder temps arrived, around 18 MPG but i think I've figured out the reasons why. Obviously your car is different being the 2.5NA but I believe the same principles are at work here. I noticed the following on multiple occasions and was concerned because my car said it was in Intelligent mode while it behaved like it was in Sport mode and I could not for the life of me figure it out... until today.

1) Longer time to warm engine=decreased mileage.
2) Heat use decreases mileage even more by virtue of raising RPM's when engine isn't at FULL operating temperature. When my XT's oil temp is less than 85 degrees celcius(about 180 F) when I turn on the heat, the RPMs rise. It will go from about 1500 RPM in I mode to 2100, which is the cruising RPM of S mode. The throttle response is also the same as if the car were in S mode! 20% throttle gets 0 on the boost meter, while if the car was truly in I mode the boost pressure at 20% throttle is about 0.3 bar or 5 psi(I know seems weird but true due to lower RPM). Futhermore, when cruising at 80kmh (50mph) the car would normally be in "7th gear" at 1700 RPM in S#, while with the heat on it refuses to make the upshift and stays at 2100 rpm in "6th gear". Finally, when I turn the heat off, the RPM's immediately drop right down to where I would expect them! Hope you guys understand all that... LOL

All said and done it shows that the use of heat while the car is not FULLY warmed up, regardless of what the blue idiot light says. will put more strain on the engine causing it to increase RPMs, this is why you're seeing the RPM's around 2500 in your car. With the short trips your car is never reaching it's full temp and so it's working harder to warm the engine AND produce heat for you.

I encourage XT and NA owners alike to test my theory, but I don't think I'm the only one who will notice it! Hope this helps but for now enjoy your car and wait for spring for the better mileage to return.
 
#23 ·
Yeah, the winter weather sucks gas. Case in point, last year I was still driving the 2001 Forester (4eat). It was an abnormally cold winter and I was getting as low as 16mpg! That's including all of the idling that we think is free (not!). In the summer, I might get up to 24-25 when driven conservatively.
This year I'm driving a 2009 (5m). When I got it this last summer, I was averaging 25-26.5mpg. Now (late chilly November), I'm averaging 22.5-24.0. This does not make me happy. However, I have a 30minute drive to town in hilly terrain at 65mph, then there's the stop-and-go in town driving that sucks up gas. It's still better than the big trucks that you see passing you. I do believe (correct me if I'm wrong) that the gas I'm using will help a bit. I found a station that sells 87 obtain without any ethanol. This would mean that each gallon has more energy than the much more commonly available, and cheaper, 10% ethanol blend. It's probably only about 1-1.5mpg better. This does not offset the increased cost, but maybe it's helping to lengthen the life of my motor's gaskets and seals.
Either way, the gas blends and colder air temps are going to eat up the fuel efficiency. Sometimes life just farts and we have to take the 'dutch oven' with a smile because there's really nothing to be done about it.
I did have a customer tell me that his Prius gets the lower-to-mid 50's in mpg during the warmer months, but that drops to the 30's when it's cold. Now there's a big percentage drop!
 
#29 ·
You say it idles at 2500 even when warmed up, what is the oil temp when it is "warmed up"? I notice the heat starts working okay around 150, but the car does not really reach full efficiency until around 190. Check the oil temp guage on the MFD and see what it is at when you get to work.
 
#30 · (Edited)
With the Winter Blend Fuels giving us lower MPG's, has anyone ever noticed if any certain brand of 87 Octane Winter Blend may give a little better in the MPG category than other 87 Octane Winter Blends? The reason why I ask, is that I have only used BP 87 since purchasing my Forester. I chose BP for a few reasons (Top Tier Fuel, 2nd Highest in Detergent Additives( Exxon #1 ) and far more BP Stations in my area than Exxon). I would have chosen Exxon if more Exxon Stations were available in my area. Must say the Costco 87 is also looking good from what I have read. The only reason I know BP 87 Octane is #2 in detergency is reading about a story done by a news station comparing fuel differences. Can't remember how old the story was, but it didn't appear to be too old.
 
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