I had an Enterprise Cobalt LS for about a month, which actually gave my mom the idea to buy an LTZ for herself.
If I reset the DIC with the cruise control on (foot operated in the LS) at 75 mph I'd get 32-33 mpg. Didn't calculate the real mileage out but that sounds about right. I drove to Grand Rapids and back as escort for my dad towing the backhoe, and doing 60 mph I got over 41 (according to the DIC).
The 2.2L is not at all slow at any speed. It's pretty smooth and quiet compared to the Chrysler 2.4L I'm stuck with now.
I wish the interior was a bit quieter. My mom's LTZ isn't any different than the LS (no power locks, power windows, nothin, but it has a DIC and automatic headlights

) even with dealer undercoating.