I have an 05 2.2L 5 speed coupe with 57k miles on it. I always consistantly get 36-38 mpg on my weekly trips to work, church, etc. Well it is slowly decreasing. Im only getting about 33 and im even driving it easier. I just changed the air filter and nothing improved. The car is running great, just burning more gas. No codes or anything showing up. Anyone have any ideas?

 

When was the last time you changed your oil? I notice that as I get closer to time to replace the filter, my mileage goes down just a little. I do not average 36-38 though, more like 31-34, but I like high revs.

Art

 

Change your oil and your spark plugs if you're due. Then fill up and report back.

 

Check tire pressure

 

That too.. basically just do all your regular maintenance, maybe use a bottle of STP fuel system cleaner as well.

 

I wouldn't use STP. Try Berryman's or Lucas.

 

Just changed oil, filter, ran fuel cleaner through it, and all tire pressure is good. I did this last week. Any other ideas?

 

Increased traffic? Hot, humid weather? Gained a lot of weight? Many externals can affect mileage as well as items listed above. They closed down a bridge here in DC and my alternate route has more stop and go and more traffic; lost 3 MPG average over the last three weeks. Just a thought for an alternative differential diagnosis.

 

traffic, stopping and going is a bitch. I go from 33 in my home city to like 25 in the city where i work due to stop and go

 

how about the fuel filter, 57k, gotta be a little dirty by now.

 

The only time a Cobalt gets 37 mpg is if you go all freeway miles.

It supposed to be about 30-31mpg with a balance of freeway and inner city driving.

Of course it is even less if it is all inner city.

Go back to all road trips and you'll have your 37mpg again.

38mpg is legendary for the 2.2, I did not know it would go higher than 37, as that is my max with all freeway miles. Maybe I used passing gear once or twice is why.

 

Spark plug /Fuel filter time... That sounds like this issue.. plus.. ITS HOT AS ***** THIS SUMMER!!!! so that isnt helping

 

I got 38.5 on a 500 mile trip, all freeway, reset before leaving but nom. is about 23-26. I have 5speed.

 

How about buying a smaller car??

durrr...

 

Get a honda FIT.
Or a prius
lmfao.