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I've been going through just about all of the mpg threads and even started searching for posts by Fr3AkAzOiD but still can't make much sense and i'm thinking of just bringing my balt into chevy to get them to take a look.

For those who don't know i have an 09 Cobalt sedan lt, i live in Washington right now so i know the hills and all aren't helping me at all but i don't floor it, coast as much as i can, alway try to keep my rpms under 3k, a/c off as much as possible (just got tint tho so will need it for the next few days), and also have my tires up to about 35 to 37 psi depending on how hot or cold it is during the day. But the dic is still telling me at max i've gotten 10 mpg, and when i fill up it tells me i only have 226 miles i can go, i know that its better to do the math myself and have and its about right give or take a few miles and i would imagine if it was running that bad then it would sound like **** but it doesn't.

I did have to unplug my battery to install my new speakers a few days ago but i would think the computer would have relearned by now. Any ideas even if its where to start looking before i bring it in?:sad2::sad2::sad2:
 

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Reset one of your trip odometers at next fill-up and you should be able to go 350 miles before next fill-up. If your not even close I would definitely bring it in. Or somebody is stealing your gas.
 

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hahaha i did that and waited to half a tank and i had gone 66 miles last time, and it's kinda hard for someone to steal my gas without the gas key lol
I was noticing this when i would have to sit in my car waiting to get released from work since there wasn't anymore to do but had the ac on just sitting there for an hour and was going to post but opened the doors and left it off and still am getting the same thing another half tank later. the speed limits here are mostly 35 with 40 tops on some streets. And i drive like 80% city 20% highway.
 

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Check what your average speed is if it's less than 20mph your mpg won't be high for sure. Maybe you should take it out on the highway for 50miles just to see. Reset your dic once at 60 mph and see what it does. It should be around 28mpg @ least.
 

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Alright well I'm going to do a run to the gas station which is about 2 to 3 miles away and post some readouts from this usb odb reader that can log data while I drive and I'll post when I get back see if it helps any
 

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alright here are the pics of the data from my computer that i thought might be helpful from my trip
 

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Looks like you spend a lot of time idling. All sensors seem to be in acceptable range. That all looks normal for a short run in town. Lucky you don't drive a Hummer. Driving habits have a lot to do with fuel economy. I mean if you stop to talk to a friend for 15 minutes and don't turn your engine off, it's going to be represented in your mpg. If you don't anticipate traffic lights and are always hard on the brakes, it's going to manifest itself in your mpg. If you always have to be first at the red light, you can be sure you'll never get great mpg. Avoid drive-through's
 

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actually the idle time youre seeing is me letting it warm up a bit and getting the computer setup and then i actually sat for a few min with it on looking at the data. And yes not that im gunning it everytime but the lights over here are something else you have enough distance to get upto the speed limit and look like youll make the light but then dont lol and i alway like sit down places more than drive thru unless im really in a rush
 

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The only thing left to do is to try it on highway, if you get better than 30mpg US your in the ball park and not much the dealer can do. But charge you for checking it and telling you everything is normal. Check your airfilter to see if it needs replacing maybe.
 

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have you givin it a oil change recently? might need one.. switch to synthetic oil if your not already! makes a big difference
 

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Even I average close to 20mpg and all my miles are city, generally short drives (~10 mins), I get on it a lot, long drives are typically ripping through mountain canyons, AND that's on E85...
I do get 7mpg on my road track but that's basically WOT all the time :)

Something's definitely up.
 

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Even I average close to 20mpg and all my miles are city, generally short drives (~10 mins), I get on it a lot, long drives are typically ripping through mountain canyons, AND that's on E85...
I do get 7mpg on my road track but that's basically WOT all the time :)

Something's definitely up.
x2, this is actually my mpg when I autox...
 

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There is probably nothing wrong with your car. If you idle, you are getting 0 MPG, if you idle a lot, it goes into your average. ( I do as in South Texas its very hot, car parked with AC on, a lot.)

Do you have the Instant MPG option? If so, check that when actually driving.

I have an Impala LT 3.5L and it gets only 16 MPG on average, but in Instant MPG, I always get more than 25 MPG, once upto speed. When accelerating, I get less than 10 MPG, lol.

I would recommend to GM that they do NOT include MPG average unless the car is actually moving, this is why some people get low averages.

E85 will always get you less MPG than gasoline.
 

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This might be a dumb question but how many miles does your car have? If over 100k you might think about changing your o2 sensors. They can affect how good of gas mileage you get. Also is your Maf Dirty ? That can have some effect on MPG's too.
 

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Looks like you spend a lot of time idling. All sensors seem to be in acceptable range. That all looks normal for a short run in town. Lucky you don't drive a Hummer. Driving habits have a lot to do with fuel economy. I mean if you stop to talk to a friend for 15 minutes and don't turn your engine off, it's going to be represented in your mpg. If you don't anticipate traffic lights and are always hard on the brakes, it's going to manifest itself in your mpg. If you always have to be first at the red light, you can be sure you'll never get great mpg. Avoid drive-through's
:thumbup: Do that ^ .....


Get this....
 
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