Wife's suby mileage differences.

Hello all,
I have a mileage "issue" with my wifs car ..1999 L. She tells me she get varying mileage and performance depending on the temp and season.
In summer if we get a cool day the next she gets easy power,if a hot day the next she says its like " flogging a horse".The mileage has been seasonally tempermental.winter BAD mileage -summer GREAT ?
Now when it come to mileage in general if it were my Crown vic I would clean the MAF and check the o2 sensors.But I have 4 cats on my car.
Is this normal ? Any ideas ?

Also do you know fo any good suby forums she can join to chat with fellow owners.No links just the name I will add .com my self.
Thanks

Nasioc is a good place for subaru owners.

As for mileage, is gas mileage fluctuating or perceived performance?

Keep in mind engines running on colder air run stronger than engine running on hot air, on a naturally aspirated engine this can have a significant effect on engine output. Even my WRX seems a little less peppy on days when the temp reaches above 90, but on days when it gets below 60 it definitely has more perk to it.

Both are. She says she notices the drop is performance trying to get on the highway,The mileage changes with seasons.She also says everyonce in awhile she will smell faint gas too...

Both are. She says she notices the drop is performance trying to get on the highway,The mileage changes with seasons.She also says everyonce in awhile she will smell faint gas too...

Has she previously owned a less powerful car? If so, the high power shock can wear off after a while. After a few months, the power output won't change, but the car will feel slower. That happened with me and my STi.