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Zerohour 07-29-2010 09:01 PM

A Quest for 35mpg (Subaru Outback Limited Sedan 2.5L auto)
:D No tall order for you guys with your Metros and Insights, but how about us with AWD and a beastly 225 wide tire.

2001 Subaru Outback Limited Sedan 2.5L auto, originally rated at 19 City / 25 HWY.

Current Mods:
1) Air intake resonator Delete (sure helps climb hills)
2) Non-ethanol Gas (Thus fair providing 7-8% over ethanol @ 1-2% more cost)
3) Driving habits
4) General Maintenance, new plugs, new PCV, regular oil chances, synthetic diff fluid (front & rear)

Last fill up 28.25 mpg, but this had a decent highway trip involved. Normal commuting comes in around 26-26.5mpg with gas friendly driving habits.

Planned Mods, all Aero:
1) Front wheel, air deflectors. Factory bumper is not as wide as tires
2) Front Bumper Lower air intake Delete - wasted factory hole, which really does not provide air into the engine bay.
3) Lower air dam, cover small bit of the engine/crossmember alot a bit of the tires. hopefully formed with a curved architecture to move air around the front.
4) Cone Covers for Side mirrors. Subaru found it apparent to stick with the Off-Road Look by equipping truck-sized mirrors on the Outback (look a pic)
5) Transparent Foglight covers. Those deep pockets can't be good for aero.
6) Rear Wheel Skirts (maybe)
7) Replacing factory muffler and unequal length header to give a little bit more uff to the car. AWD+Auto robs the factory 165HP from the 2.5L H4. I wouldn't be surprised if the car only puts 100HP to the ground. Being in PA that makes alot of issues with climbing hills. Which cause constant downshift, loss of momentum, and higher RPMs

Planning on trying to get #1 on the car this weekend, and building/maybe installing #2 as well.

I know you guys love your coroplast, but I have no access to it. I'll be using fiberglass to building my parts. :cool:

Zerohour 07-29-2010 09:14 PM

Hooray, 5 posts, so now I can share pictures!

My Subaru

Front Wheel Air Deflectors (F-WAD :D)

They need some sanding, some mounting hardware & 3M tape. Same paint wouldn't hurt either. :p

Zerohour 07-29-2010 09:15 PM

Some Facial Mockup for this Weekend. I need to start eating the cereal that no longer has boxes. :mad:

RobertSmalls 07-29-2010 09:19 PM

Actually, I don't know how I could achieve 35mpg in the Insight. Closest I ever came was 41mph, driving fast, into a storm.

My first car was a 1996 Subaru Legacy, 2.2L, 5MT. I loved that car, but the fuel consumption was out of line. By driving carefully and using a kill switch, a grille block, and a ScanGauge, I was able to get 31mpg, versus 27mpg the previous summer.

Next time you need tires, you should look at narrower ones. The Outback may have come with 225's, but the Legacy did fine with 185's. There are also LRR tires available, maybe in a silly SUV size like the Outback's.

Block off the upper grille first (someone here did a neat job in spandex), because it has a bigger impact on aero. Then block as much of the lower grille as you can.

Too bad about your transmission always downshifting. Good luck with your car. 35mpg is a bit ambitious for a 22mpg vehicle, but some folks here have achieved even larger % over EPA.

Edit: Now I see your pics! Hmm, with that foil in place it reminds me of the work of Istas. The nice thing about fiberglass is you can paint it body colored and make it look as good as OE if you're willing to spend the time on it.

Meph 07-29-2010 09:35 PM

my 2.2 1998 impreza seems to max out around 33, thats my best with lots of 80km/h rural crusing, i think 35 with mods would be possible, mines bone stock

brucey 07-30-2010 12:31 AM

You can do it, trust me. (: Your mods are starting to look very professional too!

I've got the wagon version of your car, but I think we weigh about the same. Stock anyway. Mine has a lot more steel, aluminum, and sound deadener asphalt than a factory one. You do have the option of making a 'prius shape' spoiler with yours, however.

The technique with mine to keep the torque converter locked on hills is about 65 mph up them and slowwwwwly losing speed down to about 55. It won't come unlocked and once you crest you can just coast down to the next start of a hill.

I'd also suggest either removing the mirrors entirely (camera maybe) or not bothering with them at all. It's an awful lot of work to reshape them.

busypaws 07-30-2010 12:56 AM

Lot's of low hanging fruit in the areo area. But don't forget about the low hanging fruit with "Lightweighting". Tonight I broke 200lbs removed from my 2300 curb weight mazda Protege. Look around, see what you can do without. A/C, P/S, Back Seat, big battery when a small one will do, spare tire (AAA card is lighter then a Spare).
P.S. Normal commute is 5.5 miles and 23 stop lights. I never get above 35 mph so "lightweighting" is my thing.

Zerohour 07-30-2010 09:50 PM

Meh time to build up an idea of how to make the mirrors more aero is pretty easy. Time to mock up, not too long, time to fiberglass, not too long. Probably could do the mirrors in a rough, semi-finished product in one day. There would be some cure time the following day, and then time to mount and paint, but overall could produce a product for those flat *******s in short about of time. :-p

I'll have to try the 65+ over the hills deal. Problem is that people on my commute route either want to do 55 in the 45, or they don't go nearly fast enough. And if you get one on your ass and speed up, they won't tail you at higher speeds. So you'll just end up chasing up to the next car. Its terrible how people drive in PA. Just today I had a guy on a bike, motorcycle bike, slow down get off this trottle to answer his cell phone as he proceeded to slow down to 30 in a 50 where people are doing 60...I was 3 cars back, I though the bike stalled until I saw the guy pull off the road into a parking lot while talking on his phone. People are god damn ridiculous around here.

saand 07-30-2010 10:47 PM

Zerohour, good luck, I am in the same position as you so i look forward to seeing what works for you.
Maybe some of my mods will give you some ideas too, so here they are.
I am driving a 91 mazda 626 with 2.2 L engine and Auto transmission.
EPA MPG is 22. I have currently been able to get 27.7 but i still have a lot of mods to go yet. The mods i have done so far are nice low hanging fruit, very easy to do. if i knew what i was doing at the start these would have only taken a day all up ( I messed around for 3 days trying to move to a manual steering rack then half way through i realised i should have just disconnected the hydraulic lines because the gearing is so similar between the manual and automatic racks)

current mods
- both side mirrors delete (I dont use them anyway, i do head checks)
- single windscreen whiper delete (passenger side)
- wheel mud guards delete
- flat wheel hub covers. (Small circle of flat plastic screwed onto the well hub
- removed air con which removes a drive belt
- some weight removed, all air con parts, some carpets, power steering most asthetic things in my boot
- Changed power steering to manual steering (disconnected hydrolic lines which makes turning harder but still drivable)
- reduced idle and placed switch in cabin to put ECU into diagnostic mode which stops it from compensating for low idle. Idle is down to 600 rpm from 800, Only stalled once and some threads here suggest low rpm may reduce lubrication but i figure if my engine dies or transmission dies i will just buy a new car that is already efficient then ill make it better.
- Wheel PSI increase, easy to do, little risk, slighty harder to drive but barely noticable

Driving habbits
- P&G when possible, I thought this couldn't be done in an auto but after reading some posts here realised i can. So when at speed i go into neutral (with low idle) then let it coast down. When going back into drive i rev the engine to match RPM and pop it back in, If the revs are matched little wear on transmission and no jolt from changing into drive.

I recommend getting a scanguage or some diagnostic gadget which tells you how much fuel you are using if you havn't already. I made one up myself so cant recommend a good one. It does let you work out what mods are good for you and changes your driving habbits. All cars are different so some real time feedback of what your mods or driving habbits are doing is very valuable.

The mods that worked the best for me were
- Mirror delete, mud flap delete and car wheel covers
- idle reduction as i am lights a lot in my standard commute

as for planned mods they are below
- belly pan
- front grill cover
- radio antenna delete
- cover up gaps for aerodynamics
- cold idle speed reduction
- reduction in idle when shifting to neutral in the cold
- automatic transmission gear manual control
- Torque converter control
- Improved wheel well aerodynamics

will have to see how they go, im hoping to 39 mpg or better but any improvement will be good

Im currently concentrating on reducing the idle at cold because my trips to work are short (10 minutes) and the high cold idle far outweighs any aero or driving habbit improvements.

so good luck, let us know what works well for you

Zerohour 07-30-2010 11:22 PM

Nice Saand, Looks like you're on your way!

Right now I tipped 28.25 with normal commute and highway trip driving @ 70 mph. I was in a hurry that afternoon as people we waiting on me to arrive from work. We left for a weekend trip, and everyone else was ready to go before my shift even ended! But riding around at that speed I still have highest recorded MPG to date for my Subaru! I had previous done about the same trip with normal commute on Gasohol and managed 26 to 26.5. Actively seeking real gasoline has helped a bit. But I'm going to take my normal commute MPG which seemed to be ~26mpg on real gas and use that as my baseline. If I can bump that to 30 and manage 35mpg on tanks that involve highway trips I'll consider that a win in my book. Hitting 30mpg on commute would put me 20% over factory rating for highway miles, and my commute is not all highway! So smarter driving has been paying off.

Of course all these numbers are pre-aero mods! So this is where it will begin to get interesting!

BTW I also have a nicely modified Ford Contour, American version of the Ford Mondeo, which shares quite of bit of history,parts, and architecture with the Mazda 626. :-)

Zerohour 07-30-2010 11:33 PM

Pictures from tonight, my Contour, and some of my sketches (sorry cell phoned the sketches, don't have a scanner).
Had just enough fiberglass matte to get one solid piece. Its rather thin, and since it needs to be impact resistant, I'll need to run and buy more in the morning. But it can cure overnight.


My sketches:
Okay traced that one lol

Current Aero Projects have been given proper ridiculous acronyms as well:
FWAD - Front Wheel Air Deflectors
FABB - Forward Air Bumper Block
FUBAD - Forward Under Body Air Deflector


Zerohour 08-01-2010 08:06 PM

Progress made this weekend:

Air intake setup:

skyl4rk 08-01-2010 09:59 PM

If you are looking for BIG aero gains, think about a boattail.

Zerohour 08-02-2010 06:08 PM

Air goes over the front before it passes out the back. :-) Maybe with time. I have a few other aeros to do up front first. Then I'll start playing with the exit ways

2win2rbo 08-03-2010 04:33 AM

Nice work Zerohour! We have the same quest (35 mpg) but I am currently travelling just around a very hilly city. I am about to do the belly pan mod.

Zerohour 08-04-2010 09:05 PM

So just to throw out an update: Working on surface quality. I'm trying to keep the weight down, so I won't be filling in the layers with bondo/bondo-glass. I"m sticking to smoothing it with resin, and thinning it down each time. So its fill, dry, sand, clean, glass. Slow work to say the least.

If nothing else I may just take them as they are by the weekending and mount up and go for the coming week.

Working on 3 pieces, little air deflectors for the wheels, and the front bumper block. All three may be on the weekend...*crosses fingers*

RobertSmalls 08-04-2010 10:24 PM

Fairing compound is like a dust composed of plastic microballoons. Add it to your resin to make a lightweight paste that hides surface asperities and sands easily. I love that stuff.

Zerohour 08-08-2010 02:32 PM

Working in the Garage today, hoping to be spraying some paint this afternoon.

Zerohour 08-08-2010 06:53 PM

Update: Fat man + Tyvex Suit + Warm = Lame

ugh chugging along on this project, but I might just kill me!

mcrews 08-08-2010 07:06 PM

you have a nice ride.
And you really are taking a nice comprehensive approach to the whole process.

On my 02Q45 .... 58mph is a sweet spot. After mods I can get 30plus mpg all day with the cruise control (epa 23). I know sometimes you just have to get there and you gotta go fast.
I run a 255/45/18 on factory rims. the factory size was 245/45/18. it's worth about 3.4% greater diameter which inturn lowers the rpm at cruise. I do alot of freeway driving about 75% of my 35-42k a yr. you might give it a look.

Zerohour 08-08-2010 10:29 PM

Nice Mcrews! That grill block is sweet.

I know Brucey has a Subaru almost identical to mine, and his whole front bumper is blocked off. I'm considering closing in some of the squares on the grill or pulling a hat trick from the New Chevy designs. If you notice all the new chevys have a wide bar in the middle. If you look they are all angled upwards. In the aero videos around youtube you can see the smoke trail fly up from the grill. It almost seems like some of their vehicles they are only making it look like a has a big grill. I'm considering making a "wide bar" in the middle of my Subaru grill to see if it helps at all. But need to finish up these projects first.

Oh a sad note, I've killed another power tool...this is my third orbital in 5 years. This time the internals actually melted and the metal block that held the shaft in place was no longer aligned for the motor to work properly. :-/ puts a damper on my cost savings for the mod, but on well. Partly I can sand with an orbital for four hours and the orbital can't! Worst part was I was bouncing between the Wheel deflectors and bumper block. So there were cooling cycles between. I had even been keeping it clean internally with the air wand! But alas, another one bites the dust.

The last one I killed was from clogging it up. And it sucks even more cause I ended up buying the same exact one that melted because there's nothing close but a walmart where I live. Probably will take this one back and get a better grade model or different brand all together.

brucey 08-08-2010 11:29 PM

I know normal convention says to block off the top grill first, but the stock lower bumper intake is roughly 5 times the size of the top. It was a no brainer for me.

Also, I have a trophy case on my garage walls of burned up power tools. I believe we're at 3 dremel (or dremel knock offs)

Zerohour 08-08-2010 11:34 PM

I was so sad when my first dremel died. :-( I have a new one, and I have a multi-speed one, but I got it for free. Someone had it and the cord has a bad wire in it. So it will randomly not work for a while.

I've also gone through two angle grinders, some screw drivers, a hammer, ball joint puller, tie rod seperator and some other ones along the way.

Brucey while you posted in here. You have a header on your Subaru? Do you think it helped with acheiving better MPG? I really want to get one, but if its going to do more harm then good, I don't want to buy it just yet. :p

You're in WV so you know what I mean with the loss of speed and downshifts on the hills. I have a feeling a header would help keep the engine in top gear more often.

Zerohour 08-08-2010 11:43 PM

Ahh I also have a 2nd question for you buddy! I know you've played with the Boattail, but have your played around with a straight end on the rear end of the Subaru? Something like they mention in the Chevy Volt videos. Reason being, I notice my Subi builds dirt on the bumper. And its only getting there one way, air pull it back behind the trunk. I was thinking of trying to make some sheet making edges to get the air to lift off end the car, and not wrap around that round Subaru bumper/trunk design. Have you had any considerations to this? Maybe mine is different because I have the Sedan.

brucey 08-09-2010 02:16 PM

I'd have to see a picture of what you mean on the bumper question? Like creating a kammback would help, if that's what you're asking.

My intake and exhaust is stock. Well, I did remove some of the piping recently to make room in the engine bay, but other than that it's stock. That being said, my engine has been bored .040 over when it was rebuilt a few years back, but that should be returning me slightly worse economy.

As far as the transmission downshifting, a couple things:

Do NOT use cruise control. As soon as the cruise control is engaged, the transmission goes into a different mode where it shifts way sooner than necessary. I'm not sure the reasoning behind this, but it does. It also tends to unlock the torque converter way too early too. I don't get it. But whatever.

Also, you can "train" the 4EAT somewhat to stay locked and in 4th. I can keep mine locked on 85% of mountains around here. As you're going up the hill, use your foot to control it. As soon as it unlocks (scangauge helps here too, but the tach also shows the difference) let off of it and wait for it to lock again. You'll probably lose a few MPH but it should lock back up and you can put your foot down again more. After you do this enough, it should start to stay locked forever it seems. I've gone as high as 45 on my TPS before it unlocks going up a mountain, while cruise control will do it as soon as 20TPS.

As for the header, meh. If you want it go for it, but I wouldn't expect a major increase in mileage from it. Do it for the fun (:

Zerohour 08-09-2010 02:33 PM

I have noticed that if the Subaru is ready to shift up hill, All I have to do is lift and tip the throttle back in, How the ECU and trans relays signals must tell it not to shift when it's at closed throttle. I have timed it right, and it will stay in fourth, but I'm not sure how healthy this technique will be for the transmission in the long haul.

As for an update, I have primer on the bumper block, and I still stopped to fill one few tiny bits. Its not perfect, and I could do better, but it's too damn hot and I don't have enough time if I ever want to get the block on the car. Mounting points are done, and I should be getting a call this afternoon to get Subaru color match paint from Napa. I have a feeling It's gonna be a hell of a test run tomorrow morning going to work. lol I don't see getting the paint in time to get the bumper painted, dried, and install and then still giving the car a half an hour test run tonight. So tomorrow morning will have to be it.

I have held off on the wheel air deflectors, I have them sanded out, but I am not happy with the way they are fitting or with the seam quality I'll have if I install them. I need to build a better mounting tab system and revamp the edges somehow.

So for now, focus in on getting the front block done.

redpoint5 08-09-2010 04:17 PM

Great project Zerohour. This is an interesting post to follow. However, I think 35mpg is unrealistic unless you make some drastic changes (removing AC/PS/Alt, boattail, etc).

I had a 1996 Legacy MT that would sometimes get 32mpg if I happened to do a lot of mountain miles. Strangely, my normal driving conditions would only get about 29mpg. I bought a 2007 Outback auto but sold it after 1 month because I would baby the thing and only get 25mpg (made $1000 in the sale).

Kudos for the effort you are putting into this. If it were me I would have sold the auto and bought a manual since that is the single greatest and easiest thing you can do to improve fuel economy.

Zerohour 08-09-2010 08:15 PM

Well Brucey (posted above) has achieved 38 mpg with his. And his is bored .40 from a rebuild. Now I don't expect to get the car to 35mpg city, but I do hope I can get up to 35mpg with highway driving. Which will bring the overall average of the car upward and maybe get the average up to 30's consistently.

My eco sig lies since I put in data from previous summer when I had a different commute. The car got 24-26mpg on gasohol with long stretches of Hilly two lane highways. And I did that without ever trying to conserve fuel. Right now my commute which is worse than that I got in above 26mpg on the last three tanks (26.5, 28.25, 27.5 respectively). Getting improvements that make 10-15% improvement would put me nearing 30mpg! Which is still better than half the massive transit vehicles use to go to and from work.

On a side note, no paint tonight. It is sitting primed. I ordered Color matched paint from Napa, but the store neglected to order caps/sprayers for the aerosol cans. So they have three cans of paint but no way for me to spray it. :-(

So tomorrow night I'll be painting if the weather holds up.

Pictures should be on their way shortly.

Zerohour 08-09-2010 08:40 PM


Zerohour 08-09-2010 08:42 PM

Test Fitting on the Car:

brucey 08-09-2010 10:52 PM

That looks bithcin. Kinda makes me want to take mine up a notch, and forget all this duct tape and coroplast nonsense.

What's the opposite of hot rod? Eco-Rod?

redpoint5 08-09-2010 11:22 PM


Originally Posted by brucey (Post 188098)
That looks bithcin. Kinda makes me want to take mine up a notch, and forget all this duct tape and coroplast nonsense.

What's the opposite of hot rod? Eco-Rod?

You must be the king of Eco-rodding then Brucey. What have you done to achieve the impressive mileage shown in your siggy?

I have these reoccurring dreams where I'm blissfully riding in nature with my old Legacy... makes me consider buying another one, perhaps an Outback. I hear the new model is quite fuel efficient with a CVT. Wouldn't want to buy new though because I would just end up trashing it.


Not sure this grill block is helping my efficiency.

brucey 08-10-2010 11:23 AM

I'd say it's half mods, half driving style. The smooth wheels, low RR tires, and gigantic grill block seem to have had the most effect.

Zerohour: I'm not sure if I was very clear, but when I said "let off the gas" to get the torque converter to lock back up, you still have to be on the gas a little bit (15 tps or so), otherwise it will stay unlocked. (:

Zerohour 08-10-2010 08:32 PM
Pretty Close
And of course something had to go wrong, god damn flappy winged bug flew right into the paint stream and was sprayed right into the paint. Had a moth do the exact same thing with the resin. Flew into the brush.
Side project, this always bothered me about the Subaru, You can clearly see the body color on any Outback. Its exceptionally bad on a white two tone:
Not any more!
Few shots while drying:

Overall Happy, it would have taken me another solid day(10-12 hours) to get most of the imperfections out of the surface, so I gave up. lol Paint is mediocre, but I'll try to sand out the bug and my one run and see how it looks tomorrow.

evilskillit 08-11-2010 10:23 AM

Man that looks pro. I can only hope my grill block looks as good when I get around to taking a stab at it.

cosmic_kid 08-11-2010 06:22 PM

Are you going to plexi over the fog lights?

Zerohour 08-11-2010 10:20 PM

Actually I've been pondering what to do with the fogs. The issue with plexiglass is simple. it comes in flat sheets and the car is not flat. I've been working up an idea for those and might just use someone else's velcro idea to cover the fogs, but I'm gonna do it a little nice. Right now I'm focused on getting the bumper block done.

Update for today: Cleaned up the run, cleaned up the bug and had to go down to primer :-( Got most everything sitting there ready to go. I\'m depending on using a polishing compound and then hitting it with a clear coat. Not sure how the Napa paint will hold up. Will most likely hit up the rubbing compound and give it two good coats of wax tomorrow. Should be on the car this weekend.

Also ordered something "green" but not in this forums "green" sense. Pictures will be up tomorrow/Friday/Saturday as progress is made.

Zerohour 08-12-2010 10:13 PM

Did not get back to the project tonight, had to deal with other things. Been spending a little too much time eco modding! hahaha

Should be buffing a bit tomorrow night and some wax and on it will go. Unfortunately, tomorrow is going to be the first High below 80degrees in the last few weeks. Oh well! Pretty sure I have no concern for the overheating issue.

I am also considering hitting up the you pull it this weekend and trying to find another lower air dam setup for a caprice. I\'ll keep everyone updated!

Zerohour 08-14-2010 08:20 AM

Kinda excited right now, going downstairs to install!

brucey 08-14-2010 09:07 AM

You might want to try the lawn edging from home depot for an air dam. It looks pretty good and is pretty much indestructible. Plus it\'s cheap obviously.

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