Terrible Mileage- 2007 Cobalt 2.2 Auto

[Will123w]

We bought a cobalt for the wife last year when her 10 year old Saturn finally kicked the bucket and for the most part I like the car. It's comfy, theres a decent amount of legroom in the back and it's relatively quiet.

The big problem though is gas mileage. Purely on the highway the car can only average 30 if its either perfectly straight or downhill, otherwise it hovers in the 28 mpg range.

The city mileage is atrocious, right around 15 or so. The avg. mileage according to the computer over the last couple thousand miles is 20.3 mpg.

Now we didn't get a bigger car because of mileage and I'm very unimpressed with it so far. It doesnt fall close enough to the 22/31 ratings for me to be happy, and I'm tired of getting around 200 miles to a fill up.

My question, is it possible for the dealership to reflash the computer, er perhaps something mechanically is wrong. I know though that when I take it in they will just say, oh well mileage varies. Sure it does but I got better mileage in my 95 lumina with a busted 3.1

[pinch a loaf]

I have an 05 with a 5 speed and I regularly drive 75-80 mph home. Yesterday I was getting 32.3 on my way home on the interstate. If I drive normally the car can easily get 38mpg. Don't know what to tell you. Mine is a lease and I would consider one again. For the price, I don't think you can go wrong. Obviously, the 5 speed will get a little better mileage vs. the the auto.

[coaster.n3rd]

Originally Posted by Will123w

We bought a cobalt for the wife last year when her 10 year old Saturn finally kicked the bucket and for the most part I like the car. It's comfy, theres a decent amount of legroom in the back and it's relatively quiet.

The big problem though is gas mileage. Purely on the highway the car can only average 30 if its either perfectly straight or downhill, otherwise it hovers in the 28 mpg range.

The city mileage is atrocious, right around 15 or so. The avg. mileage according to the computer over the last couple thousand miles is 20.3 mpg.

Now we didn't get a bigger car because of mileage and I'm very unimpressed with it so far. It doesnt fall close enough to the 22/31 ratings for me to be happy, and I'm tired of getting around 200 miles to a fill up.

My question, is it possible for the dealership to reflash the computer, er perhaps something mechanically is wrong. I know though that when I take it in they will just say, oh well mileage varies. Sure it does but I got better mileage in my 95 lumina with a busted 3.1

200 for a tank? My 05 with 2.2 AT gets almost 400 with my fiances driving habits (they are not good by any means) which is a serious mix of highway and city. My old 2.2 5-speed would continuously get 385 or better from a fill-up.

better have it checked out or check your driving habits.

[fenderbender]

There must be something wrong, unless your wife has a heavy foot, mainly on accelerating. Does she take off fast from a stop? That will kill your milage.

My mom's 07 Cobalt Coupe 2.2 Auto gets about 28 combined, with mainly city driving. Not bad at all, but the way I see it, there must be something wrong with yours.

How many miles are on it?

[j_granlund]

i drive my parents '05 base cobalt fairly spirited in mostly city driving and haven't averaged anything below 24 mpg.

[psece]

With my 2005 Malibu 2.2 with 4 speed auto, I get over 26mpg with my wife driving. That isn't the computer but actual mileage(with the only variable being the pump accuracy). I would say you have a problem. Do you feel the the torque converter locking at all? What rpm does the tranny shift out of first into second? Have you only had this car for the winter and do you have cold winters?

[CobaltSScrazy]

is there an engine knock? maybe that could be happening...happened to my bros 5speed cobalt. used to get 28-30 mpg combined but it has an engine knock at 25,000 miles and gets about 22.6mpg.

and GM is *** and is giving him the run around and not fixing...plus 5th gear grinds ERG

CobaltSScrazy

[sonjaab]

Does your area have "winter blend" gas?

[member12]

20 ish mpg is not bad for mostly city driving in the winter months in any car that size with an automatic transmission.

When you are sitting at idle in traffic- you are getting 0 mpg.
When you are letting your car warm up before you get in, it is getting 0 mpg.
When you accelerate heavy from a stop, it's getting almost 0 mpg.
When you drive in heavy city traffic, then I can't see any conventional economy car getting more than 20 mpg anyways.


Let's first look at the driving habits. After we have ruled out that this isn't normal winter driving, then let's see if there could be a bad gas blend or something. My experience is that 9 times out of 10, it is a change in driving habits, much like the kind of change that comes with winter driving.

If it's the car and you honestly haven't had a change in driving habits or drivers or fuel blend: Some would point to a high tech device malfunction, but I'd try to rule out things like a low tire, a parking brake that is frozen or can't disengage, a screwed up fuel filter or some other simple solution.

If thats not the case, then start the experiments. Fill it up totally at a station near the freeway and drive for 10 miles at 60 mph (relatively flat) with light acceleration and deceleration. Refill at another station near the freeway and check your mileage. Your cobalt should probably be getting at least 26 to 27 mpg. This would be a good time to keep your eye on the tach to make sure that your auto tranny is going into overdrive, and that it isn't spending too much time in a lower gear. I know that my truck will do 2,000 RPMs at 70 mph steady and 2500 RPS at 90mph steady. This kind of stuff you should know or should be able to get from another cobalt driver.

If you are still getting poor mileage in your experiement (low twenties or lower) then maybe try to bring it in to the dealer. Keep in mind that with higher gas prices, lots of people are complaining if they dont' get the advertised mileage. People don't realize how much a simple stop sign or traffic light can affect mileage.

Remember, every time you stop and idle at a stop sign or traffic light, you are hurting your fuel economy. Try to acclerate and keep the RPMs below 3000....IE, avoid the heavy foot.

[TiburonJT]

My dad rented a Cobalt and drove it to work on the highway about 80 miles each way for a few days and got bad mileage. His mileage on the highway was in the low 20 (maybe as high as 24?). He got better mileage in his truck.

[Will123w]

Originally Posted by member12

20 ish mpg is not bad for mostly city driving in the winter months in any car that size with an automatic transmission.

When you are sitting at idle in traffic- you are getting 0 mpg.
When you are letting your car warm up before you get in, it is getting 0 mpg.
When you accelerate heavy from a stop, it's getting almost 0 mpg.
When you drive in heavy city traffic, then I can't see any conventional economy car getting more than 20 mpg anyways.


Let's first look at the driving habits. After we have ruled out that this isn't normal winter driving, then let's see if there could be a bad gas blend or something. My experience is that 9 times out of 10, it is a change in driving habits, much like the kind of change that comes with winter driving.

If it's the car and you honestly haven't had a change in driving habits or drivers or fuel blend: Some would point to a high tech device malfunction, but I'd try to rule out things like a low tire, a parking brake that is frozen or can't disengage, a screwed up fuel filter or some other simple solution.

If thats not the case, then start the experiments. Fill it up totally at a station near the freeway and drive for 10 miles at 60 mph (relatively flat) with light acceleration and deceleration. Refill at another station near the freeway and check your mileage. Your cobalt should probably be getting at least 26 to 27 mpg. This would be a good time to keep your eye on the tach to make sure that your auto tranny is going into overdrive, and that it isn't spending too much time in a lower gear. I know that my truck will do 2,000 RPMs at 70 mph steady and 2500 RPS at 90mph steady. This kind of stuff you should know or should be able to get from another cobalt driver.

If you are still getting poor mileage in your experiement (low twenties or lower) then maybe try to bring it in to the dealer. Keep in mind that with higher gas prices, lots of people are complaining if they dont' get the advertised mileage. People don't realize how much a simple stop sign or traffic light can affect mileage.

Remember, every time you stop and idle at a stop sign or traffic light, you are hurting your fuel economy. Try to acclerate and keep the RPMs below 3000....IE, avoid the heavy foot.

Sorry to not get back soon I was busy yesterday, and thanks for the replies everyone!

I'll start off with the lead foot, I have been accused of having one many times and I'll admit it, but I'm not the one who drives the car. She does 85% of the time and she drives like a little old lady. She gets mad at me if the tach even reaches anywhere near 4000.

The car has 13k miles on it. I had not reset the mileage monitor for at least 2-3k so it's been a pretty good average, we do about 70% city 30% highway, so I'm not expecting a 30mpg avg, but somewhere in the 24-25 range would be more like it.

Now she almost never lets the car warm up in the morning. I figured maybe this was the reason as the car runs like crap when its cold (as did my ecotec cavalier,which btw averaged 30 mpg) so I let it warm up and restarted the mileage reading from there. I let it go the whole day as we were doing lots of driving looking around for a new place to live.



That was the result, and I was really trying to get good mileage as well. Coasting as often as possible, not using the breaks too much, estimating when a light would turn green so I could coast through. No luck the car just didn't want to break into the 20's.

To CobaltSSCrazy, I haven't noticed a knock I'll look again later today.

I live in Cincinnati so we do get the cold weather, about 20 degrees today, but we also get great summers. We've owned the car for about 1 1/4 years so we have gone through all the seasons, the mileage has been steady throughout, averaging 17mpg-20 mpg.

[TiburonJT]

Have you calculated the mileage yourself?

Originally Posted by Will123w

That was the result, and I was really trying to get good mileage as well. Coasting as often as possible, not using the breaks too much, estimating when a light would turn green so I could coast through. No luck the car just didn't want to break into the 20's.

To CobaltSSCrazy, I haven't noticed a knock I'll look again later today.

I live in Cincinnati so we do get the cold weather, about 20 degrees today, but we also get great summers. We've owned the car for about 1 1/4 years so we have gone through all the seasons, the mileage has been steady throughout, averaging 17mpg-20 mpg.

[Tomko]

Maybe someone is siphoning your tank.

[SirRaven]

Watch the instantanious fuel economy readings sometimes, it might help you out if it is your driving causing the fuel economy. Please dont have it cause you to become a dump driver, but it might help you make a few small changes to improve fuel economy without sacrificing safety and pissing everyone else off.

[GMCdriver]

My old dealership had a fuel consumption test they would do for customers to determin if the vehicle was useing more fuel then normal.

If it was, they would then do some diagnostics to determin the cause.
Some times things like a faulty sensor give the computer very bad data and cause it to run far to rich. Sometimes a faulty sensor gives the computer very bad data and causes you dash readout to be wrong.