('11+) 2012 Impreza Owners - MPG Thread!

[ans2k]

Originally Posted by SleepNMnky

From the monster of a thread under News & Rumors http://forums.nasioc.com/forums/show....php?t=2131206

Its not working for me. My cars says 32.1 but I calculated it out to be 28.7.

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[flyboy1100]

i see lots of CVT reports, how are the 5speeds doing?

[79letour]

My 5mt does really well. Around town and in rural area I think the manual gets better mileage. But on long commutes the cvt does waaay better. I say this from my experience from driving both.

[ans2k]

does anyone have experience with calibrating the mpg and avg mpg readings?? i tried doing the steps that were posted but no such luck

[ChrisAS]

I also want to know about the calibration

[o2brew]

I noticed yesterday while on a long freeway stretch that the odometer appears to be off by a noticeable amount. After 40 mile post markers my odometer only showed a distance traveled of approximately 38 miles. I checked it every 10 miles and it was off every time, from .3 to .5 miles.

If this is the case for others it would partially explain the MPG. That's 5% off, which would be 1-2 MPG.

First fill up calculated to 27.3 MPG, but if I assume odometer was off by 5%, that takes it to 28.6 which is pretty close to the displayed 29.1.

[hemophilic]

My GPS was within 1 mph last I checked and my trip is generally 1 or 2 mpg off.

[ST Eye]

I won't complain if the odo is off in my favor.

[SleepNMnky]

The method previously posted about calibrating the MPG gauge was for the Canadian models. Haven't found a way on the US models & my tech looked at me like I was nuts when I asked. I may have the service manager look into it.

I also doubted the odometer so I used my GPS & my speedometer AND odometer are spot on. My GPS has a fuel Eco gauge too which matched up with the Eco gauge on the Subaru. I wish I could blame my crappy mileage on the meters but I can't. Fingers crossed for a firmware update.

[ST Eye]

Originally Posted by SleepNMnky

The method previously posted about calibrating the MPG gauge was for the Canadian models. Haven't found a way on the US models & my tech looked at me like I was nuts when I asked. I may have the service manager look into it.

I also doubted the odometer so I used my GPS & my speedometer AND odometer are spot on. My GPS has a fuel Eco gauge too which matched up with the Eco gauge on the Subaru. I wish I could blame my crappy mileage on the meters but I can't. Fingers crossed for a firmware update.

Did you hear that one was coming down the pike?

[SleepNMnky]

Originally Posted by ST Eye

Did you hear that one was coming down the pike?

Not yet, no. One other poster mentioned his dealer thought it would be needed due to the number of people complaining there. My dealer is trying to put together #s to present to SOA after their BS line that this car has a 10k mile break in period. Once all of us at my dealer start hitting 5000 miles they're going to run fuel consumption tests & take it further with SOA.

[ST Eye]

Originally Posted by SleepNMnky

Not yet, no. One other poster mentioned his dealer thought it would be needed due to the number of people complaining there. My dealer is trying to put together #s to present to SOA after their BS line that this car has a 10k mile break in period. Once all of us at my dealer start hitting 5000 miles they're going to run fuel consumption tests & take it further with SOA.

How do you run fuel consumption tests?

[ans2k]

Originally Posted by ST Eye

How do you run fuel consumption tests?

put a known amount of gas in the car and run it close to dry or dry. i assume.

[ST Eye]

Originally Posted by ans2k

put a known amount of gas in the car and run it close to dry or dry. i assume.

It has to be more scientific than that.

[SleepNMnky]

Originally Posted by ST Eye

How do you run fuel consumption tests?

He's got it. They run it nearly dry & fill the tank to a predetermined amount of gas the tank is intended to hold so no overfilling effects anything. Then they drive the car under ideal driving conditions - or close to it (real world not simulated). They do this with 2 tanks & use the overall numbers from the 2 tanks. If their testing shows low numbers too with their "controlled" test then it's not my driving & not the driving conditions or the fuel blend.

[ST Eye]

Do they have a track to run the car? And who drives it?

[SleepNMnky]

Originally Posted by ST Eye

Do they have a track to run the car? And who drives it?

Good questions to ask. I don't know. I should probably find out who, I'm assuming it's a Subaru trained tech or manager. My dealer is close to a long, flat, rather not busy highway that I'd assume they'd take runs back & forth on but I'm not sure. I do know they keep it for a few days.

[ans2k]

sorry, my answer was very basic. but the test is very basic and cost effective. i mean they could hook up a diagnostic reader to the fuel injector to measure the pulse/spray pattern and duty cycle on a predetermine distance. but somehow, this scientific approach would probably be costly or too technical and overly complex for some. so yeah, pouring a predetermine amount of gas into the tank and seeing how far it gets you is pretty simple for me.

[pxpaulx]

Couldn't a fuel test be done by physically weighing the vehicle before/after then adding fuel to get back to the pre-drive weight?

[seaflipper]

Originally Posted by pxpaulx

Couldn't a fuel test be done by physically weighing the vehicle before/after then adding fuel to get back to the pre-drive weight?

That's how car and driver does it for their testing. Apparently using just the "fill up the tank and divide miles driven since last fill up by gallons filled" is not the most accurate way of doing it - same pump different day can result in a significant difference in how much fuel you actually get in the tank.

However, weighing your car is not a practical way for most of us to measure at home

[ans2k]

^probably not. just curious what do really really really large as a bath room scale? i just need four of those.

[BryanP5555]

so i just did a rough estimate of fuel consumption.. i had 319 miles on the car and it had said i had another 40 miles left, but i dont know how accurate it is just yet. i just filled it up for $3.96 and it filled to $53.74. it breaks down to 26.666667 MPG. Not to bad for 1/3 of the way through break-in period.

I also do more around town driving then long stretches of driving.

[pxpaulx]

Bryan

Instead of saying you paid 3.96 a gallon and paid 53.74, it'd probably be easier to just say how many gallons were purchased! Also, If I divide 53.74 by 3.96 I get 13.57 gallons - did you buy anything else in the gas station? If not, then 13.57 gallons over 319 miles comes to 23.51 mpg.

[pxpaulx]

Quick update to this current tank - still reading 33.6mpg at 205 miles (likely approx 31 calculated) - temps are also quite cold here this week, down to 33 this morning. Still giving terrible mpg for the first 2-3 miles (or minutes) of driving - still hating the pzev, but it seems that colder weather isn't having as much effect anymore at 3400 miles on the ODO. At this point I would place most blame for bad MPG during short trips/first 2-3 miles almost entirely on the pzev engine management*.

*not a complaint, just my observation! Hopefully SOA will be able to address this via a CPU flash of some sort.

Originally Posted by pxpaulx

Yep anything in the neighborhood of 45-65 will almost definitely be above 30 unless uphill or accelerating, and usually into the 40s or 50s.

Case in point: I left the house with 65 miles on the current tank, and ODO reading 29.1mpg. It initially dipped below that to 28.5mpg. I drove 65 miles today, with strong winds (upto 20 miles plus - yes some at the back of the car, but I returned home when winds were even stronger into the wind). Pulled into the garage with the ODO reading 33.9mpg. Since I doubled the current trip distance (65-130 approx) and added about 5mpg to the average mpg, that means that for this 2nd part of the current 130 trip I actually averaged approx. 39mpg. I'll even plot the trip for perusal on google maps if anyone is interested.

[RxMPLS]

Originally Posted by pxpaulx

Quick update to this current tank - still reading 33.6mpg at 205 miles (likely approx 31 calculated) - temps are also quite cold here this week, down to 33 this morning. Still giving terrible mpg for the first 2-3 miles (or minutes) of driving - still hating the pzev, but it seems that colder weather isn't having as much effect anymore at 3400 miles on the ODO. At this point I would place most blame for bad MPG during short trips/first 2-3 miles almost entirely on the pzev engine management*.

*not a complaint, just my observation! Hopefully SOA will be able to address this via a CPU flash of some sort.

I don't have PZEV and my first few miles are also really bad, typically. They're a little better when it's warm outside, though (or at least the poor mileage at startup lasts less time).

My mileage really dropped this weekend due to constant, strong, gusty, continuous headwinds (30 - 40 mpg) on my long drive yesterday. I think it went from about 33 to 28 mpg.