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Subaru Legacy/Outback: MPG-Real World Numbers



  • ateixeiraateixeira Posts: 72,587

    Mileage should improve as it breaks in.
  • First fill up on my 09 Legacy SE yielded 23.5 with 50-50 city/highway mix. The trip computer registered 26.1 for the same period.

    It's early and I expect improvement down the road but I'm wondering if the trip computer is generally this overly optimistic or there might be some other factor involved.
  • robsisrobsis Posts: 162
    We just bought an 09 Legacy w/std 2.5 engine. Our readout seems about .5 mpg high when I compare it to fill-ups (only a few, thus far...) which seems to be about where most posts (on various forums) that I've seen regarding this matter have been....usually between .5 and 1. Your 2.6 difference seems a little high in comparison to what I have read thus far. I bet it'll be better on fill-up #2.

  • You can't judge by the first fill-up. You don't know exactly how full the tank was when you picked up the car. Reset the trip meter and take an average of the next three fill-ups and compare to the computer. It should be fairly close, within 1 MPG.
  • kidalikidali Posts: 17
    Just purchased a 97 outback cause i thought it ran really well.
    Have filled it up three times now, and have calculated that I am averaging only 12.5 to 13 litres per 100k (that's 18.1 to 18.7 miles per gallon). Seems oftly low, especially when moving from my 87 Camry that was yielding me 29 miles to the gallon, even now at 22 years old).

    Anyone suffer poor mileage on these? I know they're all-wheel drive, which consumes more, but this seems lower than normal. Will a full tune-up help? The tires are properly inflated.

    Toronto, ON
  • robsisrobsis Posts: 162
    Tune up will certainly help in many plugs, wires, air filter, and a new fuel filter just upped my '98 from 19 to 23 overall...

  • xwesxxwesx Fairbanks, AlaskaPosts: 10,865
    What is the mileage on the 1997? Often with high mileage engines, in addition to those things noted above, cleaning out the vacuum system (such as PCV valve and hoses) and replacing oxygen sensors will yield better fuel economy and performance.
    2014 Audi Q7 TDI, 2008 and 2013 Subaru Forester(s), 1969 Chevrolet C20 Pickup, 1969 Ford Econoline 100, 1976 Ford F250 Pickup
  • kidalikidali Posts: 17
    The plugs were changed in january, along with ignition wires... so should still be fine. Only things I had thought of were air filter/ gas filter/ oil change.
    Thanks for the info on vaccuum system and O2 sensors. Will check it out.

    On a similar note, my gas gauge is giving severely faulty readings. From a full tank, I'll get 200k (approx 125 miles) and it will register as only a quarter tank left. I go to fill up, expecting a hefty bill, only to get $18 worth.
    Is this my fuel pump? I also get a 'whirring' noise somewhere in the back of the car when accelerating over certain rpms. First I thought it was something to do with the awd system. Now I'm wondering if it's the fuel pump doing strange things.

    Any idea what this would cost to repair?
  • xwesxxwesx Fairbanks, AlaskaPosts: 10,865
    Hmmm.... that 'whirring,' does it do it whenever you increase the RPM on the engine, or only when actually driving (i.e., car in motion)? If it happens when the car is in motion, I have to wonder if it is a noise from the rear differential rather than the fuel pump.

    On my 1996 Outback, the fuel gauge would drop much faster from F to 1/2 than on the second "half" of the gauge. I estimate that a fill up at 1/2 on the gauge would result in about 5.5 gallons, whereas 1/2 to E would result in an additional 8 gallons. This is not as drastic as you state, but it may, in part, be due to tank shape, gauge calibration, or..... ?
    2014 Audi Q7 TDI, 2008 and 2013 Subaru Forester(s), 1969 Chevrolet C20 Pickup, 1969 Ford Econoline 100, 1976 Ford F250 Pickup
  • kidalikidali Posts: 17
    The whirring seems to be when I'm accelerating past 95km/h (about 55mph)
    Actually, it's also at about 45km/h (30mph). I think you're right though. Sounds like something in the drivetrain? Differential?

    Mileage isn't exactly horrible, so I'll forgo any work now and will wait till spring.
  • kidalikidali Posts: 17
    I'm now down to 17mpU.S.g (13.8L/100km) at about 80%highway/ 20% city, and I've been ultra careful about fast starts, and sticking around 60mph (100km/h).
    Tires are balanced and inflated properly.
    Maybe it's the cold weather, but wow, at that mixture of highway/city driving, my old 22 year old junk box of a Camry would yeild me double that mileage. I'm not kidding.
    I know I've moved up to all-wheel drive, and a much heavier car and bigger 4cylinder engine, but I do believe even for the Subaru that something's wrong.
    Wires, plugs etc were replaced a year ago by previous owner.
    Any ideas? What are others getting out of their 97's? Maybe I should just take the thing to a Subaru dealer. I'm scared of getting screwed over in repairs that will get me little gains in mileage.
  • xwesxxwesx Fairbanks, AlaskaPosts: 10,865
    Well, assuming no major parasitic losses in the drivetrain (which should be noticeable), you may need to look at your vacuum system. If it is gunked up and airflow is obstructed, your efficiency is going to go way down. The PCV valve may need replacement, or you might need to run a can (or two) of SeaFoam through the engine, drawn directly into the vacuum system. Also, if your oxygen sensors are fouled and not providing accurate feedback to the engine, you will experience reduced efficiency.
    2014 Audi Q7 TDI, 2008 and 2013 Subaru Forester(s), 1969 Chevrolet C20 Pickup, 1969 Ford Econoline 100, 1976 Ford F250 Pickup
  • kidalikidali Posts: 17
    I guess I'll take it to a subaru dealer. :S
  • Purchased a 2009 2.5i OB automatic about 1 month ago (510 miles). So far the display is showing 24.3 mpg. The vast majority of that would be considered 'city' driving. Although quite happy with the mileage I would tend to think this will increase slightly once the car is broken in.
  • ateixeiraateixeira Posts: 72,587
    That's good for city driving. I bet you'll break 30 on some trips if you keep the speeds down.
  • That would be nice! My city driving mileage is now up to 24.9mpg (950 miles)
  • kidalikidali Posts: 17
    Would still like to ask any and all 97 Outback people to track and report on their mileage. I just bought mine used, and I'm still hovering around 13.5L/100km (17.5 mpg(US), 20.9 mpg(IMP) ).
    I understand it's a HEAVY car for a 4cyl. engine, and 12 years old, AND awd, but from the couple reports from others I've seen, my mileage seems poor.
    I've used fuel injector cleaners and have used gold (Shell 91 octane) gas to see if things improved, and they have, as I was near 14L/100k before (16.8 mpg US), but still not good in my estimation. I'm delaying looking at the O2 sensor or PCV valve cause I'm not sure what those repairs would cost.

    (Oh. And I would estimate this this is 70% highway and 30% city useage <rarely travelling over 105kph {65mph} ).
  • xwesxxwesx Fairbanks, AlaskaPosts: 10,865
    PCV valve replacement is cheap and easy. The part might approach $8, and it takes about 2 minutes to replace. I suspect that your low mileage is primarily related to aging sensors and poor vacuum flow.
    2014 Audi Q7 TDI, 2008 and 2013 Subaru Forester(s), 1969 Chevrolet C20 Pickup, 1969 Ford Econoline 100, 1976 Ford F250 Pickup
  • rfrfrfrf Posts: 31
    Considering 09 OB 3.0 - anyone with mpg estimates and thoughts on the power? Thanks.
  • robsisrobsis Posts: 162
    Power is excellent...I liked the 3.0 power delivery much better than the is smoother and quieter. As to mileage, I have friends getting mid to high teens around town and mid 20's on the hwy. I also like the fact that the '09 says that premium is optional; however, if it is anything like another vehicle I own with premium optional, you will see a 5-10% drop in mileage when you use the regular check into this if you don't like spending the extra money on the premium gas.
  • kidalikidali Posts: 17
    Thanks xwesx.
    you seem to know your stuff.

    You recommend a Subaru dealer, or should any decent mechanic be able to identify and replace whatever is needed?

    I'll be taking it in once the weather starts warming up a bit (and my wallet is a little more full :)
  • I test drove a 09 3.0 OB two times, two different cars. First drive was in 40 degree temperature, the second in the 20's. Both times I thought the 3.0 engine was lethargic. It simply runs out of breath above 65 MPH. Around town it's just adequeate.

    According to the trip meter, which I reset after a short warm-up, the mileage averaged around 17.5-18 MPG. Both test drives were around 10 miles long, with the Normal (Sport) setting on the SI-Drive. Both test drives were about half highway and half local traffic.

    I personally would not recommend the 3.0.
  • xwesxxwesx Fairbanks, AlaskaPosts: 10,865
    For this type of work, any good mechanic should be able to assist. If you can find a reliable independent Subaru mechanic, your car will be quite thankful. :)

    When considering how much money to throw at this problem, take a look at your driving, estimated fuel economy if running well, and mileage, then compare that to what you currently pay, and consider the difference between the two. Also consider that if the car is running more efficient, the engine will likely last you longer.
    2014 Audi Q7 TDI, 2008 and 2013 Subaru Forester(s), 1969 Chevrolet C20 Pickup, 1969 Ford Econoline 100, 1976 Ford F250 Pickup
  • rfrfrfrf Posts: 31
    Am in the middle of making purchase decision and you put your finger on one of the remaining issues for me. Have you tried SI drive Intelligent mode?
  • robsisrobsis Posts: 162
    Yes and it does fine...not sure about the reply as to the poor aspiration of the 3.0 as I have not experienced that at all. I have test driven both the 08 and 09 3.0 at 5200 ft in cold weather and they wanted to both run strong well into the 90's, when I stopped due to the speed limit on the test road....! the sport mode seemed to bring it on stronger; however, I did not notice a huge difference when I put it in sport-sharp. The Intelligent mode seems the best overall for just plain everyday, which is why I believe that Subie put it there in the first place. The other modes are fun for short periods of time; however, you can just tell that your sucking more petrol.....


  • rfrfrfrf Posts: 31
    Have read through the posts re mpg estimates fro the 3.0 - not great, at lst compared to the Sub reported EPA of 19/26. did u notice if the Intelligent mode helped w/ mpg? I bet the 3.0 rides great.
  • morin2morin2 Posts: 399
    Auto trans 2.5 first tank calculated 28.3 mpg (350 mi/12.36 gals) today, with varying speeds for break-in period. Very pleased with this & I expect to do better when temp warms up & its broken in. I'm mostly all highway, rarely touch brakes & coast to stops. Same very gentle driving with previous vehicle (Silverado 5.3 extcab 4x4) got only 16mpg.
  • ateixeiraateixeira Posts: 72,587
    That's pretty sweet, you beat my new Miata (smaller car, smaller engine, two wheels driven). I got 27 on my first tank, about the same on my 2nd.

    28+ is sweet given the size of the vehicle. Never mind that it's AWD.
  • thallbergthallberg Posts: 18
    I have a 2009 Legacy SE (2.5 engine) and only get 19.5 in town, according to the cars computer.
    I also have a 2003 VDC Outback wagon (3.0 engine) that gets 19/26 dead on.
    Kinda makes me wonder why I didn't go for the 3.0 R.
    I have no complaints about the 2.5, except you can hear the engine a bit more. I just expected better mpg.
    Do you reset the display after filling with gas?
  • ateixeiraateixeira Posts: 72,587
    We have a similar engine in our PZEV Forester, and my wife is getting around 25mpg. Not bad, for an automatic with AWD that size.

    She does mixed driving, mostly around town. Our record is 33mpg on the highway but we usually see around 30.

    I do reset the trip computer for each tank, actually that's how our Subaru is - each trip computer has it's own average.

    My Sienna is different - you have to manually reset the trip computer, and it's just one average.

    My Miata doesn't have one, that feature was new for 2009 and I have a 2008 model, so I just divide the miles driven by the actual gallons used.
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