2011 aveo5 - Engine sounds rough, poor gas mileage

Hey all,
I just purchased my '11 aveo5 Automatic a week ago (used) and have ran a tank of gas through it on the highway. about %95 highway driving (probably more) got me 28 MPG. I was pretty disappointed as I was expecting around 34 or maybe even better since I was drafting behind some trucks some of the way. My previous car which was totaled in an accident was a 07 toyota yaris which I would get over 40MPG on the highway with so I know its not my driving style.

Would this have anything to do with my engine sounding pretty rough when its idling? Also, it hesitates pretty badly when you step on the gas. Its like its starts, then bogs down, then goes...

Theres also a rattling or groaning like sound as you transition from idling to starting off coming from the front.

Would this all be something I could take it to the dealership since its still got the manufacturers warranty on it? What would I need to tell them, would it cost me anything?

Would I improve gas mileage by getting "iridium plugs" and new wires?

You will not get 40mpg in the aveo, or any car like this for that matter, if you drive 55mph, no more no less, you will see the best numbers. Take it to the dealer as it is under warrenty, though I doubt they will help much. No CEL?

No CEL. I'm not expecting to get 40MPG out of it, was just expecting to be closer to the advertised 34MPG on the highway for the automatic. 28 on the highway is a significant loss in advertised economy and just worried this could further indicate a problem.

I just mentioned the 40MPG in the yaris as an indication to my driving style. The yaris was advertised at 40MPG on the highway and I was able to achieve that, and sometimes more with my driving.

Did you test drive this car before purchase? Did it have these issues then? Where is that customer service person who was here for a hot second. Sounds like someone bought a new 2011 Aveo, had problems that Chevy gave them the run around on instead of fixing so they just traded it in to get rid of it. With the hit you take on depreciation, why else get rid of a 1 year old car?

I don't know who would even buy a new car nowadays :D

How many miles is on it anyways?

if its under warranty you need to ask dealer to do an inspection. problem with asking us backyard mechanics a vague question you will get i think its the fuel delivery system(needs injectors cleaned), its the coil packs (thats why its running rough) also its the poorly gapped spark plugs,ignition wires and so on.all these things effect performance and mpg so unless you want to start changing everything some1 suggests(800.00 worth of parts) might just want to ask dealer to look at it under warranty.

14,400 Miles on it when I bought it.

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Originally Posted by charlieb

if its under warranty you need to ask dealer to do an inspection. problem with asking us backyard mechanics a vague question you will get i think its the fuel delivery system(needs injectors cleaned), its the coil packs (thats why its running rough) also its the poorly gapped spark plugs,ignition wires and so on.all these things effect performance and mpg so unless you want to start changing everything some1 suggests(800.00 worth of parts) might just want to ask dealer to look at it under warranty.

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Yah you are totally right. i guess i was just wondering from other aveo owners if any of that was "normal" kind of stuff in case the dealership tries to tell me it is.

If you wanna look yourself, check the spark plugs and air filter first. You might as well upgrade the plugs anyways so changing them may be a good idea. But see what the dealer says, may very well be a sensor or something of that sort.

I exceeded the highway rating of every Toyota I've ever owned by about 10% (based on the new ratings). I'm nearly that much under the highway rating on my Aveo5.