frank_ster Posted November 25, 2011 Share Posted November 25, 2011 drive slower , don't let it idle. spark plugs not likely. check for gas smell leaking gas or leaking evap. Now that's thinking out of the boxer! fyi all 05 + legacy's have built in code reader Link to comment Share on other sites More sharing options...
ehsnils Posted November 25, 2011 Share Posted November 25, 2011 I have been getting about 18.5 mpg on my 07 legacy sedan, with its non-turbo (very basic) 2.5 engine. Mostly city driving, but not at all aggressive driving. This seems ridiculously low for a stock 4 banger. Any suggestions (spark plugs)? AT or MT gearbox? AT gearboxes has a tendency to consume more due to more loss, but it depends a lot on the driver too, MT gearboxes varies more since they depend even more on the driver. And driving style - city driving is hard to define by itself - is it crawling at walking speed or are you reaching the speed limit often? Link to comment Share on other sites More sharing options...
NAM Posted November 25, 2011 Share Posted November 25, 2011 Thanks for taking the time to reply. It is an automatic. No leaking gas smell, and most of the driving in the city is at between 35 and 40 mph. I have consciously tried to drive it very conservatively, but I can still only get it up to about 20mpg. Tires are at 32psi and these are summer numbers--so no long warm up or excessive idling. Just bothered that I am getting the mileage of a V6 or V8 and the performance of a 4. BTW great forum. Link to comment Share on other sites More sharing options...
NAM Posted November 25, 2011 Share Posted November 25, 2011 NB the mileage numbers for the car are listed as 22C and 29H. So getting 18.5 combined is significant drop. Cheers. Link to comment Share on other sites More sharing options...
ericem Posted November 26, 2011 Share Posted November 26, 2011 Ya should be much better, I can easily get over 20mpg with my GT all city. How does it idle under certain conditions? I am thinking maybe a vacuum leak. Link to comment Share on other sites More sharing options...
ehsnils Posted November 26, 2011 Share Posted November 26, 2011 Oil viscosity also plays a role. Fully synthetic 5W30 or 0W30 will be good. Using 10Wxx oil will have an impact on your fuel consumption. Especially on shorter drives. And if you first let the car warm up before you start to drive it will have a huge negative impact on fuel consumption since it will burn fuel without providing any driven distance. But this time of year it's a bit inevitable since you may need to warm it up to get rid of the mist on the windscreen. One more thing you should do is to do a highway drive now and then to give the car a full warm up. Start with a normal warm-up, fill the gas tank, then take it for a 30 mile soft drive at 55 to 65 mph, fill the tank again and come back with the fuel figures. That can give us some additional info, and at the same time the car would have had a full warm up. (some parts aren't getting really warm until after 20 miles of driving) and the cat would also get a nice workout. Of course - one factor that occurs on older engines is degradation of the injectors, so injector cleaner may help, but sometimes a more thorough cleaning of the injectors is needed (or replacement). But that means a visit to a specialist shop. In general it's a good idea to keep track of your fuel consumption figures since that's often the first telltale that something is degrading and a service is needed, even before you can feel/see any other ill effects. Also make sure that it's reasonably clean in the engine compartments, especially the ignition cables and coils. Use clean alcohol to clean them, WD-40 contains oil that can make things worse pretty quickly. Dirt is a good electrical conductor as soon as it attracts humidity. Link to comment Share on other sites More sharing options...
NAM Posted November 27, 2011 Share Posted November 27, 2011 Cheers for the very thorough response and the insights. Will implement suggestions and let you know what happens with mpg figures. Link to comment Share on other sites More sharing options...
frank_ster Posted November 27, 2011 Share Posted November 27, 2011 witch are more areodynamic ? wagons or sedans ? Now that's thinking out of the boxer! fyi all 05 + legacy's have built in code reader Link to comment Share on other sites More sharing options...
Rancid Posted November 28, 2011 Share Posted November 28, 2011 Maybe a dead or dying front O2 sensor could lead to bad MPG on a higher mileage car. Link to comment Share on other sites More sharing options...
Max Capacity Posted November 28, 2011 Share Posted November 28, 2011 NAM, you should be getting 22-23.5mpg. When was the last time you did a tune up ? Plugs & air filter ? O2 sensor could be a issue. I can average 22-23mpg with my 05 wagon making 280whp. Highway I'll get over 24mpg as long as I keep it out of boost. I replaced both of my O2's in the last few months and cleaned my MAF and IAT sensors, washed my Perrin panel filter. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
NAM Posted November 29, 2011 Share Posted November 29, 2011 Car has about 40k miles on it. Air filter is ok. Did a tune up last year. Will try replacing the O2 sensor as a first step. Everything Ive read seems to point to that as a possible culprit. The funny thing is, I dont remember any CEL coming up. According to Subaru I should be getting about 26mpg (normally aspirated sedan). Link to comment Share on other sites More sharing options...
Berzerklo Posted November 29, 2011 Share Posted November 29, 2011 NB the mileage numbers for the car are listed as 22C and 29H. So getting 18.5 combined is significant drop. Cheers. Just so you know those are the old fuel efficiency numbers. The Feds changed the way you calculate MPG a few years ago, so the new "adjusted" numbers for a 2007 Legacy 2.5i Auto is 20 city/28 Highway/23 Combined. http://www.fueleconomy.gov/feg/bymake/subaru2007.shtml Sounds like you are still getting a little lower than that, but just thought I would throw this out there. Link to comment Share on other sites More sharing options...
NAM Posted January 8, 2012 Share Posted January 8, 2012 So I finally got around to getting an O2 sensor installed. My garage said that the universal 3 wire I picked up online for 70$ was the wrong type so he installed an NGK. 275$ for the part alone. Ouch. He installed it and reset the computer, but after about 30 miles I am still getting lousy MPG numbers. On top of that the figures are all over the place. A slight tap of the accelerator sends me to 5mpg.I take my foot of the gas and Im at 100mpg. My question is, is this normal with a new O2 sensor? Is the computer simply recalibrating to the new sensor? Im averaging about 19mpg, which I think is still lousy for a normally aspirated 4 cyl. but it looks like I may have to live with it. Link to comment Share on other sites More sharing options...
frank_ster Posted January 8, 2012 Share Posted January 8, 2012 the correct sensor is about 130$ when looking at the instant mpg read out and you floor it yes it will go down to about 5mpg and when you left off the the throttle it will go to 100 because there is actually no gas going into your engine. with my 2.5i i can get over 34 mpg at 75 mph cruse i can also easily get 15 mpg in city driving it hard. Now that's thinking out of the boxer! fyi all 05 + legacy's have built in code reader Link to comment Share on other sites More sharing options...
PieceOfChum Posted January 9, 2012 Share Posted January 9, 2012 I am not sure if this helps at all but when I initially got my 2008 2.5i PZEV 4EAT SE I was getting freakish gas mileage 25.5 in the city calculated. Two things happened that have affected my gas mileage and I have not seen 25.5 mpg since. The first thing was I drove the car a little wildly to have some fun with it and I used the manual sport shifter. I noticed that after doing that a couple of nights my mpg was much lower. I reset the ECU and it came back up a little. Around the same time the temperature started to change and it got colder. As it got colder my average mpg's went down even more. I also noticed that my car idles very high when I first start it up so it warms up very quickly within a couple of minutes I have heat but it also is terrible for fuel efficiency. So that combined with winter gas and I am seeing around 20 mpg city out of my car. I will have to check again when it gets warmer to see if the colder weather really was the major factor. I just wanted to share because I was elated at the 25.5 mpg city driving for the first two tanks of gas (got the car in early Oct 2011) but been a little disappointed since however I do love the way the car drives and it is plenty powerfull enough for me. Link to comment Share on other sites More sharing options...
Max Capacity Posted January 9, 2012 Share Posted January 9, 2012 the correct sensor is about 130$ with my 2.5i i can get over 34 mpg at 75 mph cruse i can also easily get 15 mpg in city driving it hard. I paid $80.00 for one of my O2 sensors from Car Quest Auto Parts. And $120 for one from the dealer. 305,600miles 5/2012 ej257 short block, 8/2011 installed VF52 turbo, @20.8psi, 280whp, 300ftlbs. (SOLD). CHECK your oil, these cars use it. Engine Build - Click Here Link to comment Share on other sites More sharing options...
jhawk222 Posted January 9, 2012 Share Posted January 9, 2012 I average 22-25 mpg hwy cruising,,nailing it mpg drops to 18-20 mpg. Around town and daily commute combining both hwy/cty I get anywhere from 300-360 mi per tankful. I enjoy driving my car so I never really thought about fuel consumption until this post. Link to comment Share on other sites More sharing options...
frank_ster Posted January 9, 2012 Share Posted January 9, 2012 i'm currently driving a rental 2012 chevy cruse 1.4 and i'm getting about 16 mpg driving it how i drive my car .. sooo .. Now that's thinking out of the boxer! fyi all 05 + legacy's have built in code reader Link to comment Share on other sites More sharing options...
bkoehn1968 Posted January 13, 2012 Share Posted January 13, 2012 I'm at stage 3 and I probably average 22-24 rural roads at 2-3 mile stretches Link to comment Share on other sites More sharing options...
ericem Posted January 13, 2012 Share Posted January 13, 2012 i'm currently driving a rental 2012 chevy cruse 1.4 and i'm getting about 16 mpg driving it how i drive my car .. sooo .. there soooooooo slow. Link to comment Share on other sites More sharing options...
frank_ster Posted January 13, 2012 Share Posted January 13, 2012 there soooooooo slow. yep my neighbour has one raced it with my 2.5i wagon 5mt with a slipping clutch and won! Now that's thinking out of the boxer! fyi all 05 + legacy's have built in code reader Link to comment Share on other sites More sharing options...
Tim Caughill Posted September 19, 2012 Share Posted September 19, 2012 I have a 2005 LGT LTD Auto. I'm getting 16mpg if I'm lucky. I dont drive like an idiot. Run all synthetic fluids. New plugs. K&N a/f. Tire pressure is at 38psi. I just finished a 4wheel brake service. I don't know how you guys are getting such great numbers??? Link to comment Share on other sites More sharing options...
BigTDogg MA Posted September 19, 2012 Share Posted September 19, 2012 I have a 2005 LGT LTD Auto. I'm getting 16mpg if I'm lucky. I dont drive like an idiot. Run all synthetic fluids. New plugs. K&N a/f. Tire pressure is at 38psi. I just finished a 4wheel brake service. I don't know how you guys are getting such great numbers??? City/Highway or combined? Link to comment Share on other sites More sharing options...
Drift Motion Posted September 19, 2012 Share Posted September 19, 2012 if it's all city, then it's about right... Link to comment Share on other sites More sharing options...
fenominal Posted September 19, 2012 Share Posted September 19, 2012 '05 OBXT lowered on Koni/Swift; everything else stock: Wife averages 17 mpg city, 19 mpg mixed, and about 20-22 mpg highway--with OEM roof rack. Funny, because she is excellent on throttle and in extending mileage. This is on 91 octane in CA. For all of you, I recommend using Fuelly to track your miles and your MPG (BTW, it's MPG, not MPGs, since it is spelled mileS per gallon, not miles per gallonS). Here is my wife's Fuelly over her last 10k miles. The time she once got 25 mpg was 100% highway with kids and loaded back with camping equipment. On my '05 Stage II Pro-Tuned WRX Wagon, I can easily get 26-28 mpg LA traffic highway. I want my wife's OBXT to get 26+. Link to comment Share on other sites More sharing options...
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