Crappy Gas Mileage in Winter.....

Is anybody else having really bad gas mileage in their 2.5 GT's in the winter months? I went from having about 28 hwy / 24 city to 22 hwy / 18 city. I am doing the same type of driving as I was before, but jeez, this is a big difference.

I also just changed my differential fluids on Thanksgiving to 75W-90 Valvoline SynPower. I know that the viscosity is greater in colder weather, but this is the weight Subaru calls for. Any ideas? I have a Stage 1 Infamous tune, do you guys think I need to do a reflash and see if anything changes?

Kyle

How long do you let your car warm up for? My MPG drops significantly in winter because I let my car warm up.

Probably about only 30 seconds and then I kick it down.

I've seen this in every car I've owned.

Pretty sure its a conspiracy put on by the government and the oil companies to make more profits in the winter months when people are traveling less.

For one thing, the air is denser when it's cold and denser air requires more effort to travel through.

Yet another part, your engine takes longer to fully heat up to operating temperatures which means it's using more fuel just that little bit longer.

Lots of little things like this that build on each other to give worse MPG.

Winter blend gasoline is also responsible for some mpg loss.

Good read. Some valid points even though we don't drive semi's
http://www.petersonpower.com/docs/rmh2005-5.pdf

^ +1

Here are a couple results form a quick google search:

http://ask.cars.com/2009/02/whats-th...y-cars-pe.html

http://ecomodder.com/forum/showthrea...gas-11090.html

- Allen.

Winter blend gas and the need to run rich for longer at cold temp startups are the two main causes of winter MPG declines. That said, my previous 2 WRXs both had about a 3 MPG loss in winter, not 6 MPG.

The tune may be part of it. I have no idea of how custom tunes build in the cold-start logic (or ignore it), so I'm handwaving here, but if you have the ability to save the tune and reflash to stock it would make for a nice comparison test.

it always happens in winter. every car i owned had similar problems. winter blend gas is different. plus in cold weather it takes more time/gas to get your engine to proper operating temp. your mpg will drastically drop on short, city trips .. . i know something about it. i have 8 miles round trip to work. ill prolly get 240 miles from a full tank . . .

^^I only drive in short jaunts to work and to run errands. I only see about 18-19mpg.

Who cares cause in the winter the soobie runs like a raped ape , worth the few mpg loss in my eyes

I have to keep my boost down at 15lbs. My car rips the studs out as is! Not liking driving on studs.

Originally Posted by vduber

Who cares cause in the winter the soobie runs like a raped ape , worth the few mpg loss in my eyes

Raped ape So true.
Yep, same thing here. 5EAT, on a Cobb OTS Stg2 map, getting 18mpg in town, down from the usual 21-22.

In addition to winter gas having less power, I've heard that the denser cold air causes the engine management system to read a lean condition so the computer compensates by enriching the mixture.

how the hell do u guys get 18+ in city? Im running stage 2 eat and im down to the 16s .... but then I do let my car warmup for 2-3 minutes... until that little blue light goes off by temp gauge. =\