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

[nubsub]

Originally Posted by buran288

I just had the transmission re-flash done on my 12 Impreza as I was told it would improve the daily driveablity and reduce the somewhat harsh downs shifts that I had going down hill when taking my foot off the gas and coasting. Well yes no more of the harsh down shifts and my combination gas mileage has gone up from 31 mpg to 34 mpg BUT my highway mileage had gone from 36.7 to 31.5!!!!!!! Yes I'm going 65 to 70 mph but WOW!!!!!!!!! Oh and once it's done it can not be undone.
Just an heads up......

can you provide more info on this? what is happening to your instantaneous mileage when you are going 65-70 mph? what are your RPMs at those speeds?

it would seem that if they got rid of the downshifting when going downhill, you would getting better mileage since it would stay more in 6th gear. the only explanation i can conjure up (putting on my scientist hat) is that it's staying too often in 5th gear even when on flat ground...and so the way you are avoiding harsh downshifts, is to stay out of the 6th gear overdrive most of the time. (i know this is a CVT, but i'm just trying to simplify the idea of what "gear" your car is in while cruising on the highway).

OTOH, i have no clue how your in town mileage (or mixed driving) would get so much better.

what kind of mileage were your getting in "mixed driving" before the flash? what is your "average speed" reported by the computer on a tank of mixed driving? how many miles do you have on your car?

thanks for any clues i/we can use to see what happens with such a flash...

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[nubsub]

Originally Posted by PAO56

just another update...with my Limited HB CVT, PVEZ approaching 11K.....with my commute of 53 miles one way Im now averaging between 31-32 MPG per tank now......it still seems to be slightly improving as we are entering spring/summer.........commute is probably 70/30 hwy city......with hwy spds between 50-75 depending on the stretch of road........

thanks, pao. glad to see how the car evolves as the miles accumulate.

what is the "average speed" that your computer reports on a tank of this mixed driving?

i'm becoming more and more convinced that while not perfect, the average speed gives a decent indication of relative highway and city driving in a mixed environment.

it's way too soon to see what my mileage will level out at, but i find that for my style of mixed driving (which amounts to an average speed in the low 20mph range), am seeing 29mpg on the computer. (will see what my next tank reads for actual mileage and i still need to check my odometer against GPS, too)

when i put my early miles of this tank on with more highway miles (ave closer to 40 mph, i was in the 32-33 mpg range).

of course, other factors like a lot of cold starts (like i have for my commute to the train station) really skew the mileage downward regardless of average mph...

[ocellaris]

Originally Posted by nubsub

can you provide more info on this? what is happening to your instantaneous mileage when you are going 65-70 mph? what are your RPMs at those speeds?

it would seem that if they got rid of the downshifting when going downhill, you would getting better mileage since it would stay more in 6th gear. the only explanation i can conjure up (putting on my scientist hat) is that it's staying too often in 5th gear even when on flat ground...and so the way you are avoiding harsh downshifts, is to stay out of the 6th gear overdrive most of the time. (i know this is a CVT, but i'm just trying to simplify the idea of what "gear" your car is in while cruising on the highway).

The fuel injectors are closed when the car changes ratios (downshifts) to maintain speeds going downhill. Without this, you would hit the brakes at the bottom of the hill anyway, it shouldn't affect MPG.

[nubsub]

Originally Posted by ocellaris

The fuel injectors are closed when the car changes ratios (downshifts) to maintain speeds going downhill. Without this, you would hit the brakes at the bottom of the hill anyway, it shouldn't affect MPG.

oh, duh. you are right...the engine isn't doing any work here regardless...

(i had bought into the anecdotal evidence from some folks who said that by manually upshifting on those stretches, they were getting better highway mileage. regardless, i haven't experimented since i haven't had any real big trips with steep hills to check out this whole CVT braking issue)

aside: one thing i really haven't gotten used to with the CVT, coming from a 5spd MT, is using the brakes more to slow down the car. i regularly downshifted my MT to slow down. even at over 100k miles, i still had over half the original brake linings on front and rear of my old car!). i've considered paddle shifting downward at lights, but it's just weird and unnatural to me (although it should be easier without a clutch pedal). i wonder too if there is any long term reliability issues of using the paddle shifters regularly, as opposed to for occasional use.

[deanm11]

Originally Posted by ocellaris

The fuel injectors are closed when the car changes ratios (downshifts) to maintain speeds going downhill. Without this, you would hit the brakes at the bottom of the hill anyway, it shouldn't affect MPG.

I think there's more to it. When you are in gear and under fuel cut/decel, the drag of the engine and drivetrain is slowing down your coasting. If you would make it down to a stop point all under decel, then there is no difference to being in neutral.. but otherwise where you will be back on the gas before stopping, Neutral (or less aggressive downshifting, equivalently) may be better, allowing you to maintain a faster speed than in gear with the drag. Somewhat of an offset while in Neutral is you are using fuel to at least idle the engine. The MPG indicator pegs at 99.9 even whlie in Neutral and fuel is being used to idle the motor though.

[nubsub]

Originally Posted by deanm11

I think there's more to it. When you are in gear and under fuel cut/decel, the drag of the engine and drivetrain is slowing down your coasting. If you would make it down to a stop point all under decel, then there is no difference to being in neutral.. but otherwise where you will be back on the gas before stopping, Neutral (or less aggressive downshifting, equivalently) may be better, allowing you to maintain a faster speed than in gear with the drag. Somewhat of an offset while in Neutral is you are using fuel to at least idle the engine. The MPG indicator pegs at 99.9 even whlie in Neutral and fuel is being used to idle the motor though.

another good point if i read you correctly, the lack of downshift would give you higher speed at the bottom of the hill which means you will have less subsequent acceleration or need for fuel on the flat or uphill section that follows.

[ocellaris]

Originally Posted by nubsub

another good point if i read you correctly, the lack of downshift would give you higher speed at the bottom of the hill which means you will have less subsequent acceleration or need for fuel on the flat or uphill section that follows.

This is true, and if people want to do that, they can click up on the paddles when descending. Most of the time I want to be going the same speed at the bottom of the hill.

[ocellaris]

Originally Posted by deanm11

I think there's more to it. When you are in gear and under fuel cut/decel, the drag of the engine and drivetrain is slowing down your coasting. If you would make it down to a stop point all under decel, then there is no difference to being in neutral.. but otherwise where you will be back on the gas before stopping, Neutral (or less aggressive downshifting, equivalently) may be better, allowing you to maintain a faster speed than in gear with the drag. Somewhat of an offset while in Neutral is you are using fuel to at least idle the engine. The MPG indicator pegs at 99.9 even whlie in Neutral and fuel is being used to idle the motor though.

Coasting down hills while in neutral isn't a good idea for a variety of safety and drive train stress related reasons.

Also you can just tap up on the paddles to pick a higher gear and hold it while descending. Once you get back on the gas, it will switch back into D within a couple seconds.

[nubsub]

Originally Posted by ocellaris

Coasting down hills while in neutral isn't a good idea for a variety of safety and drive train stress related reasons.

Also you can just tap up on the paddles to pick a higher gear and hold it while descending. Once you get back on the gas, it will switch back into D within a couple seconds.

neutral, i agree is a bad idea in general (that's one reason i always downshifted even approaching a light with my manual transmissions)

although i haven't tried it, but if i understand the owner's manual correctly, i think that if you actually put yourself into the "M" mode, you can actually hold the high gear. but if you are in the D mode, it does revert, ultimately to what the computer thinks is best.

in my limited use of the paddleshifters in D mode, i haven't figured out what this "revert" mode is because there are times i have found it reverts quickly back to D and other times, it let's me stay in my preset gear for quite a while.

[ocellaris]

Originally Posted by nubsub

neutral, i agree is a bad idea in general (that's one reason i always downshifted even approaching a light with my manual transmissions)

although i haven't tried it, but if i understand the owner's manual correctly, i think that if you actually put yourself into the "M" mode, you can actually hold the high gear. but if you are in the D mode, it does revert, ultimately to what the computer thinks is best.

in my limited use of the paddleshifters in D mode, i haven't figured out what this "revert" mode is because there are times i have found it reverts quickly back to D and other times, it let's me stay in my preset gear for quite a while.

I think it switches back into D once the selected gear becomes "wrong" for acceleration, or when the selected gear would be spinning the engine under a certain RPM. When descending, I've never had it switch from my selected gear back into D until I hit the gas again (or when cruise control gets engaged again).

Anyway at this point, I am extremely interested in getting some details on that transmissions re-flash that buran288 received. If that is an actual thing and MPG goes up, I would drive to the dealer this weekend. Thought part of me think maybe they just reset the ECU and TCU.

[PAO56]

Originally Posted by nubsub

thanks, pao. glad to see how the car evolves as the miles accumulate.

what is the "average speed" that your computer reports on a tank of this mixed driving?

...

As i recall.....the average is in the high 30's low 40's....I will check at my next fillup which should be tommorrow....

[nubsub]

2nd tank up today. 227.1 miles and 8.08 gallons. hand calcs gives 28.1 mpg, computer reads 29.4 mpg.

aside: interesting to note that at around 222, the 7th bar disappeared: (5 of 12 showing): this is something i'll have to do a mental calibration of in the future to see if i can figure out consistently what the bars translate to (at least on the below half side of things). i rarely run a tank down to the warning light, but it's nice to have a rough guide (i don't trust that "miles remaining" gauge at all yet. it seems all over the place so far. not sure if it's learning my driving or...)

[ST Eye]

I drove for 7 hours today in my Impreza. The first leg of the trip I calculated 37.2 MPG!! I was averaging ~72 MPH on 90% highway driving.

[flyboy1100]

the way i see it, it has to be better than the 22.8mpg I got yesterday when filling up my buick It used to get 30 on the highway at 75, not anymore.

so honestly if i can see 30mpg averages i will be really happy!

[nubsub]

Originally Posted by ST Eye

I drove for 7 hours today in my Impreza. The first leg of the trip I calculated 37.2 MPG!! I was averaging ~72 MPH on 90% highway driving.

Great to hear!

[BIGD070572]

DGM sport 5 spd
Tank 2 403.5 miles, ind. average mpg 31.2, 13.558 gal. Calculated 29.7. Mixed driving, 30/70 city/hwy including a/c use. I didnt document the avg mph, but I am consistently 65/70 mph hwy. I'm pleased so far.

[Penguin44]

Just past first tank. Average speed 36kph. Average on computer 9l/100km.
Got 562km on the tank all city. The last bar had disappeared. There was about 3l left in the tank. Cvt base 5door. base model.

[2012 polish STI]

An air intake and exhaust will help u gain ur mpg

[ST Eye]

Originally Posted by 2012 polish STI

An air intake and exhaust will help u gain ur mpg

And you know this how?

[noahj]

Just coming up on 1000 miles on the odo, and it looks like it's getting 29 mpg on an 80/20 mix of freeway and city driving. Good enough for me.

I think the mileage estimates on the center display are generally pretty wacky, which is what is making people nervous.

[2012 polish STI]

Originally Posted by ST Eye

And you know this how?

I had a intake and a exhaust and re mapped my ecu and saw better gas mileage

[79letour]

On what car? ^^^

[2012 polish STI]

Originally Posted by 79letour

On what car? ^^^

I'm a 2010 wrx

[ans2k]

Originally Posted by ST Eye

And you know this how?

also saw this improvement in my s2000

[ST Eye]

Originally Posted by 2012 polish STI

I'm a 2010 wrx

I'm not trying to be a ball buster here, but I think it's rather premature for you to make a comment like that without having substantiating information backing it up. There are so many factors that can play into MPG. If you were truly getting better gas efficiency it is more likely due to the tune leaning out your maps and not the intake and/or exhaust.