07 2.4 auto LT TRIM
24mpg on interstate and 22.7 daily drivng, no where close to 30mpg
i noticed 3100 rpm at 79.99 mph lol
2600 rpm at 60ish, I too was concerned about lock up, I kinda expected 1800 or so like my 99 $ilverado or any 2010- 13 rental car Ive driven.
looks like im fairly normal in comparison...

 

I don't do any interstate driving but I've been getting about the same as you around town. I've got a fuel trim issue or something going on with mine (smoking a little under heavy acceleration). I was averaging about 24.5-25 before I had my last oil change and started having issues with the smoking.

 

2.2 auto lowered panel on stock tires 35 psi. 25-26 combined (never do in-town tanks). 27-29 hwy at speed limit (never higher than 75 mph though - ain't Texas fun?) Part I like if I nail throttle from low speeds, doesn't shift into overdrive till nearly 100 mph. (most of my prior cars shifted at 80)

 

mine has picked up since we came out of the artic temps
29+ mpg 45-60 mph with some stop and go

 

I have found the best MPG comes when the RPM stays near 2100. It really declines fast above that. (that's around 55 MPH for me, HA!).

 

It if makes anybody feel better I get about 14mpg in my truck,that's when I'm easy on it.
But it sounds really cool going down the road.

 

My 1st tank of gas gave me almost 26 mpg. I'm happy with that.

 

Topped off the 09 Ecotec 2.2/auto on Saturday & calculated just over 27 mpg with mixed driving. Doubt that I've driven this vehicle more than seven days since Jan 1st. Have been driving a 2.3 twin cam 'beater' truck (22+ mpg) and began to think I could lower expen$e by going more with the hhr. After doing the math this weekend while factoring in wear and tear, I don't think it's worth it to change current pattern.

Find it perplexing how much better dad's 6 cyl Buick fuel milage is when compared to what I drive.

 

I got 31.0-31.5 mpg of mostly highway driving Roanoke VA to Staunton VA, 65-75 mph when the weather was colder. Now that it's warmed up I'm getting 32.0-32.5 mpg, per the DIC. I've gotten as high as 33.4 highway when on mostly flat roads. I have the 2.2L auto & rpm is about 2600 at 75 mph.

 

Man, maybe I should get a 2.2 for commuting...

I get about 25 or 26 around the Detroit suburbs, where the driving varies from 55 mph 2 lanes to mind-numbing stoppage on the interstate. I have a basically stock SS and only occasionally hit boost.

A 15% increase wouldn't be a bad thing, though...