Low MPG

So I recently bought a CPO 2016 Legacy 2.5i premium with 11,000 miles. My first Subaru and my first CVT transmission.

 

I love the car so far. The only thing is I'm getting pretty terrible mileage on my first 2 tanks of gas so far. I'm wondering if I'm driving the CVT wrong or if something mechanical isn't quite right. Any ideas what could be wrong?

 

I will say my average speeds have been really low only a few highway trips, so average speed has been only about 20mph and in Florida my a/c is always on. My mileage has been between 13-19mpg. Admittedly I did spend some time idling in the driveway figuring stuff out/programming the radio. So I guess my usage is basically worse case scenario.

 

I generally try to accelerate as slow as possible and coast as much as possible in traffic which I'm often in. I'm hoping maybe it'll just go up next week when I start driving more normal faster speeds and longer trips.

I would take it on the highway first on a decent length drive, 30-45minutes before you start to worry about the mileage being low. Try to stay around 60-65mph and you should see at least 30mpg even with the A/C on. In most cases driving 65mph will get me a solid 34 mpg as Subaru advertises. If you're seeing under 30mpg after an extended highway trip then I would take it in to the dealer to figure out if there is something wrong. The type of city driving you described could very well get you sub 20mpg numbers so it's hard to tell just based on that.

Congrats on your first Subaru!

 

I noticed a difference in my MPG depending on the fuel brand I was using. When I sold cars I had an old manager who swore by Chevron, it was the only thing he'd put in any of his vehicles. He swore they ran better and got better mileage. I decided to give it a try in my Outback XT and I went up 3 MPG. A while later at another job I heard a coworker complaining about her brand new Outback 2.5's poor mileage and hesitation taking off from a stop. I told her about my old manager and my experience but she was pretty skeptical, nevertheless she gave it a try. A short time later she came back and said the car no longer hesitated in accelerating and her MPG went up. She dropped the generic fuels and went strictly Chevron.

 

Consumer Reports also came out with an article about the virtues of top tier gasoline: https://www.consumerreports.org/car-maintenance/study-shows-top-tier-gasoline-worth-extra-price/

It's the city driving. I get 20 on my 3.6 doing city driving, you should be getting better.

 

Up here if we stick to Sunoco, Shell or BP gas we get decent mileage. I noticed some of the other brands don't work as well.

It's very unlikely @ 11k but.. When I recently had poor mpg on my 2009 legacy, it was from some dirt or gunk on the maf sensor. Not a lot, but clearly enough that it hurt my mpg. You could take yours out and inspect it if this continues, and clean it with maf cleaner. My mpg was only off by about 2-3mpg when I had a light residue on the maf.

 

Fueleconomy.gov says 26 city, 35 highway, 29 combined for the 2016 legacy with a 4 cylinder.. your numbers are way off from that, enough that if it's a cpo, I might just take it to subaru and see what they think.

I could probably get that kind of low gas mileage here in the middle of winter in New England, driving like a maniac! I drive pretty conservatively, with a few very aggressive highway on-ramp pulls when fully warmed up to keep things clean, and it bothers me when I get below 30 indicated MPG (the indicated MPG is usually 2 MPG optimistic).

 

Idling is 0 MPG. How long were you idling for? I've noted 1/3 GPH fuel consumption while idling, so you can subtract that from your calc to see what you really got (i.e., if you idled for a cumulative time of 3 hrs playing with settings, then you may have burned a full gallon. Instead of dividing 400 miles by 18+ gallons, divide by 17 gallons.

What I would do:

Warm up yor car. Top off your gas tank, reset your trip mileage (which will reset your average MPG).

Then head straight to the highway and like the others' here have said, go for a nice 30-60 minute drive, and try to hold to a steady speed around 60-65. (or 55-60MPH is even better)

Try for flat roads with no hills, if possible.

You can either manually hold to the speed or even use cruise control if that's easier.

And just drive. No speeding, no heavy throttle. Just cruise.

 

And please report back on what MPG you got and over how many highway miles.

You should be getting a min of 30 MPG (figuring a loss of 2-3 MPG for winter gas)

I am having the same issue with my 2014. Subaru dealer says normal and I say bull schizzlle.. did extensive work so far and MAF is looking like it is tango uniform.. it is reporting normally at 2..6-2.9 grams/sec (idle) on some days and them others it is over reporting at 3.6 to 4 grams/sec. There is no way a 2.5L naturally aspirated engine sucks down that kind of air at idle when warmed up or cold at a stop in gear

 

 

get a data logger and see what your readings are for that sensor.

 

also, does your car smell like raw gas when you start it up?

I am having the same issue with my 2014. Subaru dealer says normal and I say bull schizzlle.. did extensive work so far and MAF is looking like it is tango uniform.. it is reporting normally at 2..6-2.9 grams/sec (idle) on some days and them others it is over reporting at 3.6 to 4 grams/sec. There is no way a 2.5L naturally aspirated engine sucks down that kind of air at idle when warmed up or cold at a stop in gear

 

 

get a data logger and see what your readings are for that sensor.

 

also, does your car smell like raw gas when you start it up?

 

Did you try cleaning the MAF sensor? I used a bit of that CRC MAF Cleaner last summer during an oil change while I was under the hood, it made the idle a lot smoother too.

 

My Outback's MPG tanks whenever you break 65 mph. It gets exponentially worse if you break 70-75. Luckily in NJ, most of the roads up here are 55.

 

When we took a big trip about 5 years ago to NC, we basically drove at 55-60 mph on Cruise Control the whole way back from NC to NJ (about 9 hours? maybe more?) overnight, no brakes, no traffic. I think the computer said something like 40.3 mpg.

I will clean it today when I get home. it has been my experience that cleaning may not restore full functionality...

I will clean it today when I get home. it has been my experience that cleaning may not restore full functionality...

 

What do you mean?

When we took a big trip about 5 years ago to NC, we basically drove at 55-60 mph on Cruise Control the whole way back from NC to NJ (about 9 hours? maybe more?) overnight, no brakes, no traffic. I think the computer said something like 40.3 mpg.

 

I understand this topic is about MPG but....I would have called an uber if you drove 55-60 for 9+ hours. Time is worth much more than $20 of savings in gas.

 

 

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even though you spray it, it does not remove 100% of contaminates and they tend to build up quickly again especially if the coating is damaged in any way

 

I understand this topic is about MPG but....I would have called an uber if you drove 55-60 for 9+ hours. Time is worth much more than $20 of savings in gas.

 

Not sure how an uber would have saved time though unless you fly or take the train. But flying these days sucks. And when you arrive you would rely on transport for hire.

I'm not trying to hijack this thread but this is related. What are the thoughts on this?

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Not sure if op checked all the maintenance items but when I got mine preowned the air filter was in need of replacement and that could affect the mpg. I also put new tires on to replace the oe tires and I lost like 3 mpg avg so that had a substantial effect.

On my first 2015 Legacy 2.5i Ltd with 13k on the odo when I traded it in for a 2016 2.5i ltd. Now my 2016 at 18k I get the same MPG as I was getting with my first one since the day one I got it. Thinking after 1000k break in it would get better, nope! countdown to the next 1k, on and on, no improvement. between 24-25mpg combine 40cty/60hwy, with only 15% traffic jams. My wife drives very easy on the gas when I drive I use eyesight 90% of the time even in the city. We are in a lower altitude below sea level and no hill but only has hwy ramps/ bridges. I only use Sam's, Costco 87 octane gas, recently I switched to non-ethanol. Car runs smoother, a bit better MPG but my two tanks with non-ethanol I get 24.9mpg combine. I'm so disappointed to go through the same experience on both 6th gen legacy. I did write a letter to SOA yesterday if I will experience the same issue on the new 2019 Ascent with the false claim MPG. I hope SOA comes back with something or I may be looking into a lawsuit?

... false claim MPG.

Not at all. My wife and I consistently get EPA mileage or slightly better year round in our 2015 Legacy 2.5 and 2016 Outback 2.5. The biggest single determinant of fuel economy is the driver's right foot ... on both the gas pedal and the brake pedal.

It's important to keep in mind how warmed up your car is too. It takes me about 15 minutes of driving to get up to full operating temperature (~200F oil temp). For example I have a very short commute to work - about 8 minutes of all city driving. On a typical summer morning I get around 25mpg according to the computer. The same trip in the winter gets me around 18mpg. If I am fully warmed up from another drive I get over 30mpg from city driving even with some stop lights.

 

There are way too many factors from everyone's personal situation and driving style to say that ~5mpg difference from what the sticker advertises for mixed cit/hwy mpg is a problem. My mom gets around 18mpg average on her legacy, but she does short city driving trips in a very hilly area.

I live in Louisiana, so mostly very hot and humid, we rarely see any freezing temperature maybe once or none every year. Like I said we drove it easy and when I drive I use Eyesight so it's not aggressive driving at all.

I live in Louisiana, so mostly very hot and humid, we rarely see any freezing temperature maybe once or none every year. Like I said we drove it easy and when I drive I use Eyesight so it's not aggressive driving at all.

 

You say that your driving includes 40/60/15 city/highway/traffic. Do you use Eyesight while traffic is speeding up and slowing down or during traffic jams?

 

I have found that Adaptive Cruise Control is VERY inefficient when it comes to accelerating and braking. It tends to want to speed up to your set speed quickly, which is counter-productive, say, if your car begins to speed up quickly after someone in front of you changes lanes, even if there's another car going slower not too far ahead. This would force Eyesight to waste gas accelerating, only to engine-brake or, worse, brake soon after. I've experienced this; the worst being after someone exits. ACC takes forever to unlock the exiting car, then accelerates briskly, only to slow down quickly, soon after, when I catch up to traffic again. Very inefficient...

 

Adaptive Cruise Control also tends to be a little aggressive with braking, especially if you're going moderately faster than the car in front of you when it sees the car.

 

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My wife is a much better driver than I am. By that, I mean that she's more conservative and timid on the road; never any road rage; never any aggressive moves. However, she doesn't drive as efficiently as I do. By that, I mean that she, like most people I see on the road, will tend to maintain speed all the way up to a red light, slowing traffic, etc., braking only when necessary. I don't mean to say that she treats the gas/brake pedals as on/off switches. She's a smooth driver, and I have no issues being a passenger while she's driving; I don't find myself stomping on an imaginary brake pedal on my side; I simply think to myself (never out loud) that I would have let off the gas many feet earlier.

 

She typically gets 2-5 MPG lower than I do. Even with 200+ miles on the trip meter, I'll see the MPG drop by a couple of MPG after she drives for a few days. She also tends to idle more than I do, which doesn't help. I start'er up and drive; when I reach my destination, the car is immediately turned off. The only time this changes, is if it's REALLY icy and cold outside or really hot and I've got the wife and kid with me.

 

As an example, I tend to drive really early or really late in the day. When there is no one on the road with me, I make it a game to see if I can use my brakes as little as possible. On familiar routes, I know when to let off the gas so that I don't have to brake on highway exits, turns, etc., while also not having to speed back up because I began engine-braking too soon. I did this yesterday on an uphill trip one way, downhill on the way back, and was able to get an indicated 35 MPG (with ~12 miles on the trip meter and ~ 30 MPG indicated MPG to begin with.)

 

I don't like to bother other drivers, however, so I normally brake as late as possible upon exiting the highway, so that people behind me don't have to slow down unnecessarily; same goes for making turns. I signal well in advance, but drive normally when the roads are congested. For the same drive as mentioned above, I usually achieve high 20's MPG, maybe just above 30 MPG, since it's very hilly and, with people behind me, I can't vary speed and coast through hills, like I do when I'm alone.

 

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Sorry for the long-winded post. My simple point, is that I can personally change my MPG for a known drive by up to 5 MPG just by how I *(am able to) drive. I'm not talking about aggressive vs hyper-miling; I'm talking about the same exact speeds (no stop and go traffic or slow downs), with the difference being how I accelerate, coast and brake.

Well, I only drive the legacy maybe once every 2-3wks for about 10-15miles with no traffic on early morning weekend. I used to drive the legacy often to work use eyesight for traffic jams. But that's not the case as I don't drive it often to affect. My wife is a patient driver, even I use Eyesight when I have to ride with my wife in the Legacy I rather drive, otherwise, I can't stand it. lol

Well, I only drive the legacy maybe once every 2-3wks for about 10-15miles with no traffic on early morning weekend. I used to drive the legacy often to work use ACC for traffic jams. But that's not the case as I don't drive it often to affect. My wife is a patient driver, even I use ACC when I have to ride with my wife in the Legacy I rather drive, otherwise, I can't stand it. lol

 

Fify Eyesight is always active unless it temporary disengages where ACC is manually turned on.

 

Laughing at oneself and with others is good for the Soul![emoji2]

I tend to drive really early or really late in the day. When there is no one on the road with me, I make it a game to see if I can use my brakes as little as possible. On familiar routes, I know when to let off the gas so that I don't have to brake on highway exits, turns, etc., while also not having to speed back up because I began engine-braking too soon. I don't like to bother other drivers, however, so I normally brake as late as possible upon exiting the highway, so that people behind me don't have to slow down unnecessarily; same goes for making turns. I signal well in advance, but drive normally when the roads are congested.

 

You are obviously my long lost twin and we were separated at birth I do all those things as well. I especially smiled when you said "I make it a game to see if I can use my brakes as little as possible" .... because I used that exact expression to a friend of mine just recently.

I also find the Eyesight is too aggressive, so I've used it maybe 5 times. I get mid-high 30's (car calculated) consistently, and I am 80% hwy/20% city. I use AC and keep my windows up. I ease onto the throttle and ease on the brakes - I too play the MPG game. I am 1 mile above sea level and my 25 minute commute is fairly flat. I work 6a-2:30p M-F so traffic is USUALLY flowing well.

 

Tank #1 at 4mi

Tank #2 at 564mi 33.6mpg

Tank #3 at 790mi 36.1mpg

Tank #4 at 1126mi 35.9mpg

Tank #5 at 1642mi 36.2mpg

Tank #6 at 2014mi 36.7mpg

Tank #7 at 2642mi 38.1mpg

Tank #8 at 3067mi 36.3mpg