Fuel mileage drop with no apparent cause

[Randal5579]

I used to get 300+ miles to a tank of fuel on my 2006 Vibe automatic, which averaged about 30 mpg.In the last few months my mileage has dropped considerably to about 250-260 miles per tank.I've changed my air filter, checked tire pressure, driving habits are the same, no warning lights have ever gone off... but I'm still getting crappy mileage. I bought this car to save on fuel, and with the gas prices steadily rising, I'd like to get my mileage back.Does anyone know what I should do?I haven't talked to the dealer yet, but should.I know to expect a drop during winter, but should it be this much of a drop?Please help.Randy

[Kamikaze]

I get in the 30's mpg in the summer... right now I'm getting between 20-26mpg (depending if I'm in town or hwy) I drive with a light foot, and have a scanguage, but can't seem to do much better. if I figured it out... worse mpg (20) to a tank would give me 260 miles... at 26mpg (quite a bit of hwy) that's about 338 miles to the tank. Don't know if this helps you out at all, but thought I would tell you what I'm getting.

[northvibe]

yup in the "winter" i got crap mileage too, 2x's. Even with my new car I get 20's mpg's for the winter. Its the nasty gas they use :/ cant wait till summer!

[Renthorin]

You will also get worse gas mpg in colder weather

[Sublimewind]

Winter gas.... Different formulation, everyone in the north is going through it...

[Mavrik]

cold weather, winter gas, leaving the car idling. it runs rich when cold... etc.do you fuel up at the same place or where ever you are when you need gas? stick to one gas station and see what happens. I use Chevron and get decent fuel mileage out of it. Can't wait for summer fuel and warm weather though. I only get 200 a tank now while in the summer I get 250+turbo and heavy foot don't help.

[keithvibe]

colder air... denser air... more drag because of it... there is a post on MO about this very question.. most of the converstation is above my head but it's good reading... http://matrixowners.com/index....59&hl=

[WaveAction]

i get crappy mpg too in the winter, specially for warming up and stuff, when was the last time you changed your oil??

[Randal5579]

I appreciate everyone's input.On a trip over the weekend my mileage was better, still not where it was, but better.The weather was a little bit warmer too, so that may very well be part of the problem.I changed my oil about 1,500 miles ago, and the car only has 13,000 miles on it for a 2006.It's just hard to watch your mileage drop so much while the pump prices just continue to climb.Again, thank you all for the input.

[coldmm803]

do all gas stations now have like 10-15% ethanol in the gas? cause ethanol will reduce gas mileage too or if the stations in your area recently switched to having it in it

[nate06]

I have heard that O2 sensors going bad can cause a large drop in fuel mileage without tripping the CEL. I don't know how much the ones on the Vibe cost but if they are pretty cheap you might try that.

[garnermike]

In my 06 Vibe and my 07 Rondo and my 93 Protege for that matter. I took the advice of some very good mechanics I know, and ran the best (as in most expensive/most hyped) fuel injector cleaner I could buy off the shelf, at slightly over the recommended dilution strength, through two consecutive tank fulls. Mileage shot back up to expected levels on all three vehicles.My mechanical aces say that the quality of gasolines is very poor these days, especially with ethanol additions being made, and when the price per gal. spikes upward, and in colder seasons (water condensation becomes an issue).

[Randal5579]

I have taken 2 trips the last 2 weekends and my mileage has improved quite a bit.Both weekends were warmer weather, and I got almost 29 mpg the 1st weekend, and almost 31 this last weekend.I haven't changed anything other than the items that I had mentioned before.Maybe the weather is a major culprit.I still plan to try the fuel injector cleaner though.Thank you all.Randy