A Quest for 35mpg (Subaru Outback Limited Sedan 2.5L auto)

[Zerohour]

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.

[Zerohour]

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

My Subaru


Front Wheel Air Deflectors (F-WAD )










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

[Zerohour]

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

[RobertSmalls]

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]

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]

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]

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]

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]

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]

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. :-)