Gas Mileage...

[ScoobySnack]

Replace plugs ngk g power, (need ngk wires), new coil pack, new fuel filter, new fuel pump. Feel the power back, but not the mileage. Wondering if I should reset the ecu? What else could I do? Maybe replace the 02 sensor? No trouble codes or anything... so I don't understand why I'm not getting better mileage.

[gryffinwings]

Replace plugs ngk g power, (need ngk wires), new coil pack, new fuel filter, new fuel pump. Feel the power back, but not the mileage. Wondering if I should reset the ecu? What else could I do? Maybe replace the 02 sensor? No trouble codes or anything... so I don't understand why I'm not getting better mileage.

Replacing the O2 sensors could help, if they are old that is or just at high mileage, even if your car is not showing a CEL then your O2 sensors could be just within operating limits so changing them could help mileage. Also catalytic converter efficiency could be down and that lowers MPG as well. How many miles do you have on your car?

[jey]

What car do you have and what gas mileage are you currently seeing?

[d1giPhux]

Sad story.. gas mileage sucks with these cars. I'm lucky if i get around 20-23ish mpg with my BD.

[ScoobySnack]

98 legacy 2.5 gt sedan. BD! Getting around 20-23 both freeway and town. Wondering if I need to replace anything else... O2 sensors may help?

[d1giPhux]

thats probably as good as your really gonna get .. depending on how much lead your foot has in it. mine has quite a bit.. so i get close to 20.. never really been too much above that. sometimes on the freeway with cruise.. but.. meh. subarus arent exactly super gas efficient.

[99SUS SFD]

I've been getting around 20-21 all city driving with a lot of steep uphills. That's with the roof rack on.

[green97gt]

our 97gt w/ 155K(or so) gets 21.6MPG regularly

dads SVX w/ 191K gets 20.1MPG

dads 07 outback legacy w/ about 30K gets 24MPG

[rudgers73]

98 legacy 2.5 gt sedan. BD! Getting around 20-23 both freeway and town. Wondering if I need to replace anything else... O2 sensors may help?

If you drive like a wimp you might get 26. I average 22-24 summer, 21-22 winter. I just think of it as a Subaru tax haha. It's the price you pay for torque, control, and AWD awesomeness. Safety is always nice too...

[ScoobySnack]

Sure don't fall under the whimp driving then. Good to know guys thanks for the reply.

[DLC]

My BK4 gets 28-29MPG.

My BE6 would average 25-26MPG, but has gone over 30MPG with %90 highway driving.

A better intake and high-flowing exhaust do a lot for economy, but so does your driving style.

[d1giPhux]

I dunno how your getting those numbers.. but damn.. lucky you! I just use my bike for MPG / fun!

[DLC]

The BE6 had the Cobb CAI, lightweight flywheel and pulley, with Cobb Street cams, EL exhaust, high-flow cat and a nice-flowing exhaust. Chances are it's running a bit on the lean side of what the ECU can understand, so the power I am getting was very good for the amount of fuel.

Lower restrictions in and out and having to rotate less mass also helps, not to mention lightweight wheels and a few other tricks.

[gryffinwings]

I'm getting a bit under what DLC is getting, but I also use the next octane up, 89, even though not tuned for it "properly", I get better knock prevention even though I don't have it, and apparently my car seems to run better on it and gets higher MPG.

[95USsubaru]

i got my 95 bd up to 27 mpg and that was a 50-50 hwy&city. usually tho its about 24-25. but it is just a FWD L however yes, im from NJ so i was born with a lead foot haha. check ur O2 and thats prob it. good luck on that

[d1giPhux]

I dont think the o2's make a huge diff. I have brand new ones.. maybe got like 1mpg more.. nothing noticeable.

[DLC]

Oh yeah, I always ran mid-grade on the BE6. With all of those parts it was definitely running lean and having some pinging with the regular unleaded.

[Benfolio]

Jesus. I have a lot of lead in the right foot and my BD got 21-22 but in the winter. Otherwise 25-26. Saw 29 on a road trip but I drafted a semi for about 20 miles. :smt005

The BK just got 28 going down to the Subaru parade, driving inthe parade, then to Chicago afterwards.

[seattlelegacy2.2]

hmm, kelly blue book specification page says 19 city, 26 highway for my 95 awd legacy wagon.
dang, somehow I swear when I was looking for these, I thought it said 23/28 :smt013
oh well, awd I guess. I like how the tank fills up really high for low dollars though, small tank I guess

[redclaw05]

What grade gas do you guys run.

I was never told what to put in so I put 93.

But if I can run 87 or 89. I would rather do that instead.

Btw. I own a stock 99 bg legacy wagon.

[Huffer]

Btw. I own a stock 99 bg legacy wagon.

Put in 87.

[mrpyb]

After redoing the heads i've got as good as 30mpg highway and i consistently get 27 for my city driving (which is still all in the country) :smile:

[Wiscon_Mark]

hmm, kelly blue book specification page says 19 city, 26 highway for my 95 awd legacy wagon.
dang, somehow I swear when I was looking for these, I thought it said 23/28 :smt013
oh well, awd I guess. I like how the tank fills up really high for low dollars though, small tank I guess

The KBB specs may be adjust to this new phony system that the EPA is using that highly underestimates the mileage on cars. 23/28 is the original spec from when the car came out though.

Oh, and the tank isn't really that small, it's 15.9 Gallons. I just find that the gas light goes on very early.

[anothernord]

[quote="seattlelegacy2.2":12by72af]hmm, kelly blue book specification page says 19 city, 26 highway for my 95 awd legacy wagon.
dang, somehow I swear when I was looking for these, I thought it said 23/28 :smt013
oh well, awd I guess. I like how the tank fills up really high for low dollars though, small tank I guess

The KBB specs may be adjust to this new phony system that the EPA is using that highly underestimates the mileage on cars. 23/28 is the original spec from when the car came out though.

Oh, and the tank isn't really that small, it's 15.9 Gallons. I just find that the gas light goes on very early.[/quote:12by72af]

23/28 is almost exactly what I see, when I'm not on boost that is. I find that when the needle reads on the "E", I have used about 11.5 gallons.

[ouch1011]

My average for all city mileage with the 4EAT is about 20-21mpg. All highway I got around 26 on my last highway trip, but that was at 75mph with the A/C. The 4EAT also tends to hold gears for too long, so for my average driving it shifts about 3500-4000 rpm for the 1-2 an 2-3 shifts.

[anothernord]

I recently got 25 going to 14,000 feet; mostly on boost. :grin:

[rudgers73]

I just got 28.7 coming from Pittsburgh back to Rochester. A/C on and cruise at 73.

Best yet! :smt004

[ouch1011]

My friend with an STI has a hard time cracking into the 20s. Guess thats the downside of having low compression and really, really sticky tires. I laugh at him, then he tips slightly into the throttle and leaves me in the dust, then I cry.

[anothernord]

My friend with an STI has a hard time cracking into the 20s. Guess thats the downside of having low compression and really, really sticky tires. I laugh at him, then he tips slightly into the throttle and leaves me in the dust, then I cry.

It's surprising how much the tread characteristics of tires affect mileage. Going from my stock 195's all-seasons, to my 225 Winterforce tires, I noticed a consistent 1-2 MPG decrease around town.

However, I have heard of plenty of WRX's that have reached 400 miles on a tank.

[rudgers73]

It's surprising how much the tread characteristics of tires affect mileage. Going from my stock 195's all-seasons, to my 225 Winterforce tires, I noticed a consistent 1-2 MPG decrease around town.

However, I have heard of plenty of WRX's that have reached 400 miles on a tank.

Friction is a powerful thing. Friction is directly correlated with drag which directly counts against momentum. One linear vector against another. It is the same relationship that causes your flight from Buffalo to NYC flying in the same direction as the wind to be 20% faster than a flight home against the wind.

Did you know that most production cars use about 40% of their horsepower just to push air out of the way? The Bugatti Veyron has 1001 HP, and it needs about 725 of those horses to make it even possible to go from 150 mph to 250 mph. The faster you go the resistance of wind goes up exponentially.

I bet you could get 40 MPG if you put 165's on all corners and put a big cone on the front of the car to cut through the wind haha.

[anothernord]

Easily. The front end isn't exactly aerodynamic; I think its drag CE is 0.40 or something. At least it has a lower frontal profile when compared to large, tall cars.

[green97gt]

put on about 1K miles on the 97gt (163K) over the long weekend, drove to alabama and back.

we got about 25MPG steady.

at the halfway mark(when we got there)

the motor was making a very dismaying :smt011 knocking noise, sounds to me like crank knock.

i changed the oil and put some lucas oil stabilizer in it, and it shut right up. i intend to post a video when it starts making noise again, it wasnt TERRIBLE but it was there. mot prominent right off idle, between 1k ans 2500 RPM. iv begun shopping for another motor as well.

but hey, the little "warwhorse"(spelled correctly) did 85/90 mph the whole way, made damn good time...

cheers fellas.

[Mikey97D]

I've been towing a lot lately. I've been averaging anywhere between 19-23 mpg combined towing & regular driving. When not towing, I've been averaging 24-25 mpg. My combined average for 2009 is 23.7 mpg.....not very good. I'll be checking my air pressure next.

[jey]

I bet you could get 40 MPG if you put 165's on all corners and put a big cone on the front of the car to cut through the wind haha.

http://www.aerocivic.com/

[SplitSecondDsm]

I dont think the o2's make a huge diff. I have brand new ones.. maybe got like 1mpg more.. nothing noticeable.

A bad 02 sensor can make a world of difference. When they go bad, they throw codes and cause the car to run really rich low throttle maps; I had a bad o2 in my talon, didn't realize it, did a wot pull, came back down to low throttle and boooom almost shot the exhaust off. Same deal with bad grounds, anything that causes a lack of spark/too much fuel will kill mpg, I blew a hole in a 3'' stainless catless thermal turboback exhaust because of a lose negative terminal.

Cliffnotes, bad 02 sensor = mad rich = terrible mpg. Later model awd subarus only get ~20-25 mpg anyways, they're heavier and autos/more displacement sure doesn't help either. I get around the same in my talon that weighs 3000 lb.s with awd, 20-22mpg out of boost city/highway, 4-8 driving hard lol. My fwd subaru gets 30-35 mpg.

[Grafton]

thought i'd chime in with a chart :D since i started tracking my MPG

high 29.2
low 19.2
average 23.2

http://img199.imageshack.us/img199/8619/mpgs.jpg
I forgot to add it to the chart, i got a different intake a week or two before the headers just so people know ...

[97LGT]

Averaging 75mph with a 4eat I easily get 30mpg.
Yesterday I averaged 85 and got 27.

[Grafton]

checked my plugs they were .010 out of gap, and i reset the computer. we will see if i get my lost mileage back

when we took the wife's obs (4eat) down to georgia in june it got 30 and 31 on both interstate fill-ups we were driving @ night without the AC on the way back up i had repaired the ac ( georgia is f***ing hot ~115 heat index about everyday ) it only got 25 and 26 on the interstate tanks

[Navi271]

hmm.. 23mpg is about what I'm getting too.. It was weird. I installed the msd coil and gas mileage seemed to go up!(20 to 25mpg) Then as soon as I started thinking about putting in the non fouler sensor thingy the good gas mileage started to go away. I was WAY confused. Now I don't have that P0420 CEL on anymore and still 23mpg.. and that's on a good day..

[hallowpoint]

i see low 20's. that with 50/50 city highway driving.

[anothernord]

Latest tank with Supercharger and lead-footed city driving: ~21 MPG. This is untuned with lots of 10:1 ARF action.

Highway I see 26-27.

[badbasser98]

2009 3.0R (5EAT) w/ approx. 2700mi

23 city
29-30 @ 60MPH
25-26 @ 70-75MPH

not too shabby :cool:

Old scoobs:

2007 STi

21 city
25 highway

2007 WRX Ltd.

25-27 mixed driving. Never went on a long highway trip.

2002 Legacy GT

23 city
27-31 highway

[Navi271]

So this might help some ppl out... My car was stock with 14" steelies with about 25mpg average, got new 17" wheels and new ebay headers. Got the P0420 CEL. My gas mileage went to about 20mpg. I got an O2 spacer which got rid of the code (I still don't have a code with the new high flow cat too) but the gas mileage never came back no matter what I did.

Now, my car was recently lowered. The 17's actually raised my car up with stock suspension and there was a pretty good gap between the wheel and the fender, like 2.5-3in. With the lowering, there is maybe a 0.5-1in. gap. I noticed that right away my car didn't catch the wind as much as it used to, AND after a few gas fill ups, my average gas mileage was back up to 25mpg! Yay for less air resistance!

So maybe bad gas mileage could be because of aftermarket wheels! (going from a small wheel to a bigger one) At least in my case, lowering your car makes it look good and saves you money! Thats my 2cents for the day...

been hitting 25-28 city while throwing a p0106

[TGX4776]

I got about 25mpg on my last trip all highway at 70mph

[subie/legacy]

I see about 20-22. 10%highway 90% city. very short trips, and most definitely not granny driving.

[HeresMyMind]

Tires play a huge role in MPG specially on Highway. I get 24-25 city and 28-32 highway. with my 99 gt wagon. JDM 5 speed swap. 4.44 final gearing. highway sux though. at 65mph im at 3300rpms. but in the city i can be cruising around town at 37mph in 5th

-B

[DarkPhoenix]

Mixed city/highway I average about 23-24 mpg with a nasty exhaust leak and a whistle. This is me doing about 70-75 in an Outback wagon on stock size tyres.

[TGX4776]

My tires probably play into my gas mileage as plus I believe on top of bad cats and bad o2 sensors I have an exhaust leak. Soon to fixed though

[Dead91silvia]

I get 20-24 on average, city and highway... I just did a road trip to eastern Washington (about 900 round trip) and on the way over I pulled 28.8 with my 98 BD GT... Thats with cruising at 78mph and also hitting 110-115mph a few times. I averaged about 90mph for about 30 miles. =) All it really has is a K&N filter and the car has about 224K...

Call me crazy, but I think I'm getting better MPG without my bug guard o_O

[Navi271]

ok so, NEW THEORY!

Remember when I said this:

So this might help some ppl out... My car was stock with 14" steelies with about 25mpg average, got new 17" wheels and new ebay headers. Got the P0420 CEL. My gas mileage went to about 20mpg. I got an O2 spacer which got rid of the code (I still don't have a code with the new high flow cat too) but the gas mileage never came back no matter what I did.

Now, my car was recently lowered. The 17's actually raised my car up with stock suspension and there was a pretty good gap between the wheel and the fender, like 2.5-3in. With the lowering, there is maybe a 0.5-1in. gap. I noticed that right away my car didn't catch the wind as much as it used to, AND after a few gas fill ups, my average gas mileage was back up to 25mpg! Yay for less air resistance!

So maybe bad gas mileage could be because of aftermarket wheels! (going from a small wheel to a bigger one) At least in my case, lowering your car makes it look good and saves you money! Thats my 2cents for the day...

Not so sure about that anymore. I mean, I'm sure it helps, but that as much as I was saying there. My problem was that my P0420 CEL came on, gas mileage went consistenly to 20mpg. Got an o2 spacer, CEL went away, but gas mileage didn't. It did come back when I was lowered, but I forgot! I put on the high flow cat too which, in the process, we had to upplug the o2 sensors. So NOW I think just unplugging them and resetting them made them realize there is no code anymore and to go back to giving me 25 mpg!

[anothernord]

Some food for thought relating to air intakes and MPG:

The way my supercharger is set up when the electric clutch pulley is off (aka no boost), the engine has to pull air through the lobes of the supercharger to get air, basically its the worst restriction to an air intake you can come up with, If I rev the engine, I can actually see the SC pulley turn as a result of the engine sucking air through and spinning the rotors.

Even with this restriction, I've still been getting respectable MPG. I've logged 30+ MPG on the highway pretty consistently, even with 535cc injectors. City Mileage has averaged at 23.5-24 MPG.

Anyway, the biggest factor of gas mileage is your driving style. If you easy on the gas from stop lights, and take your time accelerating, I guarantee you'll gain a few MPG's. On the highway, instead of blasting down the left lane at 80, set the cruise at 68 and chill in the right lane. There's 3-4 MPG gained right there.

[98outbackpdx]

2 tanks ago all city and i got my worst tank yet....15.2mpg all city, but i only average 23-24 mpg mostly highway

[LiCelsior]

ok so, NEW THEORY!

Remember when I said this:

So this might help some ppl out... My car was stock with 14" steelies with about 25mpg average, got new 17" wheels and new ebay headers. Got the P0420 CEL. My gas mileage went to about 20mpg. I got an O2 spacer which got rid of the code (I still don't have a code with the new high flow cat too) but the gas mileage never came back no matter what I did.

Now, my car was recently lowered. The 17's actually raised my car up with stock suspension and there was a pretty good gap between the wheel and the fender, like 2.5-3in. With the lowering, there is maybe a 0.5-1in. gap. I noticed that right away my car didn't catch the wind as much as it used to, AND after a few gas fill ups, my average gas mileage was back up to 25mpg! Yay for less air resistance!

So maybe bad gas mileage could be because of aftermarket wheels! (going from a small wheel to a bigger one) At least in my case, lowering your car makes it look good and saves you money! Thats my 2cents for the day...

Not so sure about that anymore. I mean, I'm sure it helps, but that as much as I was saying there. My problem was that my P0420 CEL came on, gas mileage went consistenly to 20mpg. Got an o2 spacer, CEL went away, but gas mileage didn't. It did come back when I was lowered, but I forgot! I put on the high flow cat too which, in the process, we had to upplug the o2 sensors. So NOW I think just unplugging them and resetting them made them realize there is no code anymore and to go back to giving me 25 mpg!


hmm im gettin 20mpg with 80% highway driving. i also have the p0420 from installing headers. so u just unplugged ur o2 sensor?

[ouch1011]

Some food for thought relating to air intakes and MPG:

The way my supercharger is set up when the electric clutch pulley is off (aka no boost), the engine has to pull air through the lobes of the supercharger to get air, basically its the worst restriction to an air intake you can come up with, If I rev the engine, I can actually see the SC pulley turn as a result of the engine sucking air through and spinning the rotors.

Even with this restriction, I've still been getting respectable MPG. I've logged 30+ MPG on the highway pretty consistently, even with 535cc injectors. City Mileage has averaged at 23.5-24 MPG.

Anyway, the biggest factor of gas mileage is your driving style. If you easy on the gas from stop lights, and take your time accelerating, I guarantee you'll gain a few MPG's. On the highway, instead of blasting down the left lane at 80, set the cruise at 68 and chill in the right lane. There's 3-4 MPG gained right there.

That's because its only a restriction under a pretty high throttle load.

Under strictly city driving, I get between 18-20mpg. I don't drive like a tard, but I do get up to speed quickly, and certainly not in the most fuel efficient manner. Cruising down the freeway, I get 30mpg at around 70-75mph. Basically a stock EJ25D, full engine-back exhaust, 5mt swap with a 3.9FD, STI wheels with 225-50-17 tires. And those MPG numbers are after correcting for the speedo inaccuracy.