Gas Milage Problem?????

[lordsaber]

Hello everyone, its me again, my car is a 04 base vibe, standard trans. i use 91 octane fuel cause i like to think it makes a difference my problem however is lately it seems like im burning gas faster, for example usually when i fill up i can go 50 miles before the gauge even drops below the full mark, now i am currently at 73 miles into the tank and am at 3/4 a tank.It have noticed this for a few weeks and am wondering is it something related to my car, perhaps the air filter? or is it the oil companys just getting cheap. thanks for all your help.

[joatmon]

we could debate the value of runing 91 in a base, but it's been done before, I won't go into that.In my opinion, the number of miles it takes for the needle to start moving, or the miles from fill up to 3/4 tank depends at least as much on how full you fill up as it does on your actual MPGs. If you really want to track a trend in your gas mileage, you have to track multiple consecutive tanka of gas and average them. Each time you fill up there is a variance, you can't fill it up exactly to the same point every time. Maybe with the weather warming up the pumps are shutting off faster than they used to. I have found that pumps at different gas stations shut off at different fill levels, even different pumps at the same station shut off differently. But you need to see how many gallons you put in, compare that to the number of miles you got out of it, and average at least a couple tanks in a row to get rid of the pump shut off variability. You want to get to miles per gallon, not gallons per fill up.

[Daox]

I couldn't agree more. Miles per gallon or any distance with respect to volume of gas is the ONLY way to measure fuel effeciency accurately. Distance per fillup (without knowing exact volume) is a horrible way which seems very commonly used by people. Driving 'till the needle moves' is also not accurate. Keep a running log of your mileage and see when it changes drastically to know if something is wrong or not. Like joatmon said, every pump will turn off at a different time. Its very likely that you just didn't get as full of a tank of gas.

[kevera]

If your really concerned about mileage.I would invest in a gauge(scangauge or equiv) to actually tell if there is a problem or not.

[Whelan]

Not to mention unless you drive the same exact road the same exact way each and every day for couple tanks you will not get the same results. Did you accelerate to pass people more often, used more throttle during on ramping. Sat idling in traffic one day or another. All these can be factors as well. Sometimes I drop at 50 others I can almost pull 75-80 before it moves. But I consistently pull within 10-15 miles per tank of my average. So far the avg. is 290 and I have done 300+ and I have done 280. So it is so hard to tell unless you have a mileage meter like the SGII to tell you what your true MPG are. Otherwise it is all just averages. Also note that what they tell you on the sticker is not precisely what it will be. I can't think of the # of factors involved actually:AltitudeGas BrandOctane Level# of gallons in fillupType of DrivingWeather (temperature)Brand/Type of tiresTire inflationStd/AutoCruise on/offO/D on or offI would personally not put anything but 87 in the tank, its not necessary for higher grade. Sure you may squeeze a few more miles out of the tank, but when it is .30 to .50 higher per gallon than 87, that cost becomes negligible.

[mathteacher'04vibe]

Keeping a running average is the only way to go. I agree with what others have said about sitting in traffic, driving harder, pumps shutting off at different times, etc. With my Camaro, I get 29 mpg on one tank of gas, then 18 the next. Is Getgo's gas that much better than Sunoco's? I think not. My Vibe ranges from 26.5 mpg to 31.5 mpg and I drive the heck out of it 90% of the time. The variances occur when I squeeze in that extra 58 cents worth, or my right rear tire is 10psi low, or when I sit in Giant Eagle's parking lot with the A/C on for 30 minutes, or when I run around town in 1st gear in my auto trans. since it sounds so sweet with the new header and exhaust.Average it out over time to truly tell. The needle moving is not the way to go.

[JesseWHHS]

i get arliuydn 200 - 215 a tank. thats not... good. haha. when i get my vibe back, imma find the problem I guess. getting an extra 100 miles a tank should would help me with money. haha

[dianebrat]

add my vote to "you have to keep a log, or it don't mean squat" camp.You GOTTA write it down and crunch the numbers, even for those folks that are picky about "and i fill to 1" under the rim" I'm not that picky, but at 6000 miles, I get a receipt every fill up, and I toss the miles on it, and reset the trip odometer, and it will average out, even if I vary how full I get it, as long as I stop when the pump clicks off the 2nd time. Averaging is the only way to go.Diane