I've taken my Cobalt on only two fairly long highway drives, about 4 hours each way. And I've noticed that my gas mileage is horrible, pretty much the same as city mileage. I dont mind the mileage I get in the city, but I'd think highway fuel economy would be a lot better.
On the highway in cruise control at about 70MPH im seeing 27-27mpg, is that normal. Is it simply because its such a small engine, and only a 5 speed transmission that it just revs high? I see RPMS close to or even above 2500 if i remember correctly. This is with a selectable tune running in stock mode. Only other mods are K&N drop in filter and catless downpipe and catback system from MPX

 

2.2? 2.4? or 2.0?

 

i think an LNF. iirc mpx only makes catbacks for the lnf's

 

ah atleast you know your cars dart. im thinking do to mods and maby cold air its useing more fuel. im stock TC gets 28 mpg average with no boost driving, has been 34mpg during the summer

 

yes sorry, i drive a 2009 turbo.

 

Are you from Ontario? How long ago did you take those trips? If they were recently, then you may have had winter gas + cold air + speed. All those would contribute to the lower mileage.

My car was getting 27 mpg at 70 mph, cold air, winter gas. A full tank would give me 360 miles, halfway mark at 180 or so.

 

yes I'm from Ontario. One trip was in October, the other just this past week. So I'd say temps around 40F. Which I guess is pretty cold air. Maybe slightly warmer. I guess I'll have to see if anything changes this summer as I do some more highway driving. I would assume its winter gas I'm using as well. I only fuel with sunoco 94.

 

Most likely from the cold air as the air is denser so you need more fuel. My fuel mileage goes down in the winter too even on low trips.

 

Have you tried to do a trip with running the tune? I noticed that you said that you have a catless dp on, and that can throw things off for the stock tune.

On long trips with mine, i average over 30 mpg. I have seen as high as 37 mpg. I did a trip a few weeks ago, going I saw 32mpg and coming home I averaged 29.5 mpg. Coming home the wind was affecting the car, as it was a windy day.

On the highway you should see around 2500 rpm near 70 mph. My car appears to eat gas when I go over about 74 mph on cruise.

Also, was the boost gauge moving a lot or staying low?

 

I have a 2.4 and I was avg. like 28 highway on 70 cruise...but we had a pretty nice couple days here not too long ago and I.took a little trip and my mpgs went up by the time summer really gets here and all the winter gas is out then eveything should go back to normal