Gas thieves?? Low gas mileage / MPG

[MyTi82]

Hey guy/gals

so just as the title suggests, i am getting rather low MPG's and i was wondering what may be causing this. when i first got my car i was getting on ave 23-26mpg mix city/hwy. now i am getting about 19mpg city/hwy. i have done the what i could think of and have searched for any other ideas but didnt see anything new.
i have changed the air, fuel and oil filters. also have new spark plugs and O2 sensors. in fact all the maintenance/mods i have done within the past year should have increased my MPG instead of decreased it. i still get plenty power n pep and i dont generally rev her past 3500rpm while driving.

i have changed the cat and muff with high flow ones. did O2's at the same time. just before it got cold i changed the oil and fuel filters and spark plugs. i use 89 octane gas. i recently put in a K&N air filter thinking that was the last piece.

i thought it was the fuel filter because i could sometimes smell gas and thought there might be a leak there. when i replaced it, it did look a lil stained liked there was a backflow.

i thought maybe the car was running a lil rich since there is a faint gas smell in the exhaust, but i could be mistaken. any help is appreciated.

[John_in_VA]

The winter gas additive package might be contributing to the poor mpg.
http://ask.cars.com/2009/02/whats-th...y-cars-pe.html
http://www.theoildrum.com/node/2964

[John Firestone]

The engine is also tuned for premium fuel, which may aggravate matters, and is less efficient during its cold phase. Might that explain some of the drop?

[vsonix]

to be fair, even 23-26mpg seems a bit poor, I average in the early 30s combined on standard 95 octane unleaded.

[MyTi82]

Originally Posted by John_in_VA

The winter gas additive package might be contributing to the poor mpg.
http://ask.cars.com/2009/02/whats-th...y-cars-pe.html
http://www.theoildrum.com/node/2964

when did this start? i never knew there was a summer/winter gas mix.

I know last winter i didnt have this issue. come to think of it, i didnt see this gas drop till i started using the AC this summer. i stopped using the AC cuz i kept getting CEL coming on and the MPG decreased.

[familytruckster]

Mine has dropped 3-4mpg (33 to 29) in the last few months. I usually just blame cold air. On my mazda I put a SHAI (dryer duct from header feeding inlet to airbox) and the car got the normal 35mpg summer milage during the winter months.

[John Firestone]

Originally Posted by vsonix

to be fair, even 23-26mpg seems a bit poor, I average in the early 30s combined on standard 95 octane unleaded.

I thought 95 RON was something like 91 AKI, which would be about halfway to premium from the OP's 89 regular.

[pdxmotorhead]

Originally Posted by MyTi82

Hey guy/gals

SNIP
i have changed the air, fuel and oil filters. also have new spark plugs and O2 sensors. in fact all the maintenance/mods i have done within the past year should have increased my MPG instead of decreased it. i still get plenty power n pep and i dont generally rev her past 3500rpm while driving.

Its a BMW. Drive it like one, if your short shifting your fouling plugs with fuel or carbon You should see 5K rpm just about every time you drive it.

Mine gets mid 30's at 75 to 80 on the freeway... 24 around town.
Wide tires suck fuel.... Skinny hard tires save fuel.

I run premium when the outside air is over 65 under that I run 89.

E10 fuel Sucks the big one..... (10% Ethanol) 15% is worse...

I find that name brand fuel does a little better than the cut rate stuff in Oregon YMMV.

Dave

[John_in_VA]

9 reasons why your winter fuel economy bites!

[3.2TI]

I would also check your air filter to make sure it is getting enough air and not blocked from old and dirty. Also make sure your tire pressure is at the recommended tire specs. These 2 simple maintenance tasks help increase mpg.