Gas Mileage problem??

Hey guys, I know this is touchy subject and wanted to get your input. I have searched all over this forum and looked in many threads. But many of them are based around the GT.

 

I just bought an 07 2.5i with 27k on it. I expected to get around 25 mpg average and this was one of the reasons i changed to this car and many other reasons. I came from a WRX with many many mods including a full PPG straight cut tranny. I would get about 23 MPG from this car. I bought the 07 and i get about 23-24 on a FULL 300 mile highway trip and i drive very conservative now. (i have been told i drive like a grandpa) In city/back rood driving i just noticed im getting about 18MPG. I changed the air filter and oil but is there anything else you have run into with gas mileage problems. I have checked the tire pressure and will prob change the plugs but how much could that effect it with only 27k on it.

 

any input would be great

Hi Geoff -- here are a few links to mileage threads from the N/A subforum. Hopefully you find something you can use. It sounds like you have already hit the high points (new oil, air filter, plugs, tire pressure).

 

http://legacygt.com/forums/showthread.php?t=79810&highlight=mileage

 

http://legacygt.com/forums/showthread.php?t=66767&highlight=mileage

 

g/l

Quite a few things come into play and you can;t change them.

 

Winter blended fuels play a part of it.

 

Also the ECM has a huge role in it as it pretty much controls everything and takes readings from and adjusts timing, a/f, etc and that effects mpg.

 

Also what type of fuel you running? Same brand everytime?

They are all different brands but i dont buy brands that are "no name". Is there any that you guys say is better and only use?

 

As for the ECM, could it be a problem with it. The car was a New York City car so idk about gas there but what about gunk in the injectors? Any recommendations on fuel injector cleaners that work?

 

Thanks

Geoff

They are all different brands but i dont buy brands that are "no name". Is there any that you guys say is better and only use?

 

As for the ECM, could it be a problem with it. The car was a New York City car so idk about gas there but what about gunk in the injectors? Any recommendations on fuel injector cleaners that work?

 

Thanks

Geoff

 

I generally stay away from costco/Sams club, Wawa and buy Exxon, and Shell. Everyone sells winter blend fuels. In a nutshell here is a little tidbit that describes winter-blend fuel.

 

The difference between summer and winter-blend fuels has to do with the Reid Vapor Pressure of the fuel. RVP relates to the volatility of the fuel. The more volatile a fuel is, the more likely it will evaporate as the temperatures increases or rises. Of course this can harm the ozone and all. Summer fuel aka gasolene has a lower RVP and it is less likely to evaporate when compared to the higher winter fuel. Of course the less RVP it has, the more energy and thus increase in fuel mileage.

 

 

 

 

There should be no need to clean the injectors, but it wouldn't hurt to seafoam the engine(not sure if that will help).

 

As for the ECU, No. The ECU controls how the air/fuel delivery, etc is depending on the data it receives from all of the sensors(knock, cam, maf, iat, a/f and 02, etc) and adjust accordingly. That is why it is tough to diagnose MPG loss. Also you have other issues

Listen to Blackfang, he knows what he's talking about.

 

I just gave up my 06' Baja Turbo for the same reason. I now own an 08' Legacy 2.5i SE with 15k on her. I am averaging around 22-24mpg around town and 34mpg on the highway.

I dont know if this could be a factor but i have 3 different tires on my car, they are all the same size. Could this effect gas mileage?

I dont know if this could be a factor but i have 3 different tires on my car, they are all the same size. Could this effect gas mileage?

No but if they all are not within a 1/4 inch in circumference they could toast your transfer clutches.

 

Not sure if they will bring some light, but the Wifey and I went to MD today for a Memorial for a friend of hers and the subie averaged 24 mpg which is off of the 29-31 mpg I have done in the summer.

A 5mpg drop sounds kind of steep, Blackfang. If it were my car, I would think I had the beginning of a problem. You would consider that normal?

 

OP: +1, listen to Blackfang. That's why I stayed out of the discussion once he got involved. He knows his stuff!

I wouldn't consider it a problem being my car is well maintained regularly and I have seen that kind of drop. Some of the minor things we can control is ensuring tires inflated properly, air filter is clean, and using a quality fuel.

I am getting new all seasons anyway which will fix the crappy 3 different tires i have now. Maybe ill see a little difference. I will be doing the spark plugs in 2000 miles. That should eliminate if there is any problems.

Plugs may help, but are good til 60k. It won't hurt to put new ones in if you have the extra coin.

Black is right, I have seen this drop also, I am getting 23.7 on the meter, was getting 29 plus in the summer. I do have 225's this beast also.

I usually get in the low 30's on the hiway with my 06 Legacy but I do notice with Chevron and detergent fuels I get much lower, maybe thats the issue.

UPDATE:

well I got new all-season conti DWS tires installed about 600 miles ago and my mileage has improved greatly. I went from 23-24 on full long highway trips to now i get 23 city40/highway60 and 28 mostly highway.

The car had three different types of tires on it and they were junk.

 

I am so pumped for addressing my mileage problem

maybe Winter fuel? On my 08' SE I went from getting 30's on the highway down to....19-21....real bad. it literally just dropped off one day. from what I can tell, it is the winter fuel mix. I did fuel up in MA (Im living in VT for the winter (stratton)) and noticed a climb in fuel economy for the day. I guess we will see come spring and the summer mix

I have noticed a significant drop in gas mileage as well. I'm averaging 21-23 mpg with a mix of about 60%/40%, city/hwy miles. It's a little disappointing as I was consistently getting around 26-28 when I got the car in Oct. of 2008.

 

I replaced my plugs recently and did not notice much of a difference, but they were due for a change anyway.

 

Maybe my foot is getting heavier? However, I'd like to know it is just winter blend fuel.

winter fuel + increased viscosity of all internal fluids in the lower temps causing greater friction + warm up times = lower mpg

I have noticed a significant drop in gas mileage as well. I'm averaging 21-23 mpg with a mix of about 60%/40%, city/hwy miles. It's a little disappointing as I was consistently getting around 26-28 when I got the car in Oct. of 2008.

 

I replaced my plugs recently and did not notice much of a difference, but they were due for a change anyway.

 

Maybe my foot is getting heavier? However, I'd like to know it is just winter blend fuel.

 

I don't see a need for concern. Sounds about right during the winter with that type of driving. I am going on a road trip this weekend so I am going to check myself just to see where I am at.

I averaged 27.92 mpg this weekend. 70% highway/30% city