2006 Aveo dissappointing MPG

Our 2006 Aveo is only getting MPG's in the mid to upper 20's. It's a hatch back with auto trans, we run reg gas. We took a trip from Indiana to NJ last Oct and got between 27 & 29MPG. Avg speed was prob around 70mph. Typically tho 80% of the driving is by me back & forth to work which is 24 mi and 95% interstate driving at 70-75 mpg using cruise control. The other 20% is my girlfriend driving around town. She tends to use jackrabbit starts and hard braking, I on the other hand, watch the tach as I accelerate to keep it under 3,000, and cruise around 2600 rpm(70 mph). Her habbits are getting better but last tank only gave us 22mpg. Tires are in good shape and properly inflated. I'm sure the a couple MPGs can be attributed to the "Winter Blend" oxygenated gas but we still seem to be way below par.
I am going to change the plugs 'cause I don't think they ever have been changed and I have heard of an over tightening issue from the factory causing them to crack and lower fuel economy.(Posted on Edmunds Forums)
Any other suggestions/comments would be greatly appreciated.
Thanks!
Ray

27-29 is not bad if you are going that fast (going 55mph would net you over 30mpg easy on the highway) It is normal to see mid 20's in city, but 22 for that kind of driving is okay. No car gets "good" city mpg's anyways, I would not be disapointed with those numbers though, the dealerships/EPA will always "lie" about MPG numbers.

welcome to the forum btw!

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Originally Posted by manray57

I have heard of an over tightening issue from the factory causing them to crack and lower fuel economy.(Posted on Edmunds Forums)

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I would like to see this..

the numbers you have sound about average for the users here, especially for an automatic, and the speeds you drive.
If you want better, what are you comparing too? some of the hypermilers are getting much better, but they also coast downhill with a backwind with the car shut off :P

Thank you both for the prompt courteous replies. I figured the speeds driven had the most to do with the mpg and told her that they were prob going by the 55 mph limit, however my driving is mostly on interstate 69 out here in Indiana where the posted limit is 70mph. I'll take the mid 20's mpg rather than take the chance of getting run over by a semi. I have included the link for the Edmonds forum relating to the AVEO MPG and what their members had to say.
Chevrolet Aveo Real World MPG - Car Forums - Edmunds

look at replies #260 for the spark plug theory and reply #265 for the shift point theory

the transmission shift points s the more correct answer, specifically the torque convertor locking in each gear. You really should NOT be hitting 4th gear in real city driving.

the spark plug theory is bs imho. the aveo needs spark plugs often, i'm due again. but the "machine" breaking them...

What the heck, I did not know you needed a "machine" to change the plugs ;)

This post made me lol...

"Replying to: randydriver (Apr 16, 2006 6:26 am)
I drive a 2009 Chevy Aveo LS, 4 door, sedan, 4 cylinder 1.6 liter Ecotec engine. It has a manual transmission, 5 speed.

I get 42-46 driving 65-70 mph on interstate or highway all the time since buying it, checked it numerous times on long trips. I have never got below 33 mpg on a tank of gas. Driving in city usually ranges 33-35 mpg, city and highway usaully average 38-40 mpg on tank of gas. That would be like 60-70% highway and 30-40% city driving. Live in St Louis, MO area".

I would gamble a large sum of money that this person is trolling.

And be careful about talking about shift points/transmissions, things tend to get a little crazy :D (or what type of oil you should use as well).

Most people wonder why small cars don't get better mileage. The answer is simple its physics. A small car is usually designed with steep windshield angle"read resistance" also being short in length the car naturally creates more draft at the rear "read Drag". Also the faster you go the harder your engine has to pull to overcome these two forces. I have a lincoln town car thatgets around 28 MPG on the highway when I'm cruising to Florida. My aveo got about 30 mpg Guess which I drive to florida. Now around town is a whole different ballgame. Sports cars are designed long lean and raked back. Thats why the corvette gets on avg 24 MPG's and still has 400 to 500 Hp on tap but the smart car barely gets 35 mpg's with about 100 Hp. So until we see smaller cars with some incredible aerodynamics thats just the way it is.

Oh by the way welcome to the forum!!!

Thanks for the welcomes!

I don't find the highway numbers to unreasonable for a sedan without AC in a warm area without many hills. The city numbers are high, but "city" means something different to everyone.

I don't care what the EPA allows Chevrolet to put on the window sticker, a sedan will always get better highway fuel economy than a hatchback with the same powertrain.

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Originally Posted by thehunterooo

What the heck, I did not know you needed a "machine" to change the plugs ;)

This post made me lol...

"Replying to: randydriver (Apr 16, 2006 6:26 am)
I drive a 2009 Chevy Aveo LS, 4 door, sedan, 4 cylinder 1.6 liter Ecotec engine. It has a manual transmission, 5 speed.

I get 42-46 driving 65-70 mph on interstate or highway all the time since buying it, checked it numerous times on long trips. I have never got below 33 mpg on a tank of gas. Driving in city usually ranges 33-35 mpg, city and highway usaully average 38-40 mpg on tank of gas. That would be like 60-70% highway and 30-40% city driving. Live in St Louis, MO area".

I would gamble a large sum of money that this person is trolling.

And be careful about talking about shift points/transmissions, things tend to get a little crazy :D (or what type of oil you should use as well).

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I just do not see 42-46 ever happening, unless the car was being towed.....;)

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Originally Posted by wylee

a sedan will always get better highway fuel economy than a hatchback with the same powertrain.

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How so? I'd like to see some hard numbers on this.

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Originally Posted by thehunterooo

I just do not see 42-46 ever happening, unless the car was being towed.....;)

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I've done it with my hatch. Not a fluke, a 3 tank average over 42mpg. It is painful for me to to drive that slow. A sedan could do a little better because of the body shape.

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Originally Posted by YnotVW

How so? I'd like to see some hard numbers on this.

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The drag coefficent is lower on a sedan body shape so if all other things are equal, the sedan will do better.

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Originally Posted by YnotVW

I'd like to see some hard numbers on this.

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Did you miss the second part of this? I'm pretty good with physics and still cannot come up with how this is true. Just looking for a study that proves that a sedan is more efficient.

I've got no study handy nor have I found one that specifically addresses this. What I do know is that, based on Craig Vetter's research, having an abrupt end to a vehicles back end (as is the case for the typical hatchback shape) significantly adds to drag as opposed to a longer more tapered rear end.

The more I think about, my original statement was probably too broad, but I stand by the principle of it as it applies to the Aveo. A Toyota Prius is a hatchback with a very low drag coefficient but it is not shaped like what I consider a typical hatchback car; the rear slopes down nearly to the point where a trunk would be on a typical sedan.