If you think a newer Chevy Cobalt SS can fit the wife and (two kids tops) kids - then I would STRONGLY recommend that.
My car is tuned to 20psi turbo boost (stay away from the supercharged ones, they are doggies) and STILL gets 30 mpg on the highway when I am not into it.
The car runs 13's at the track and I drive it to work 70 miles round trip every day.
I can't say one bad thing about the car at all.
The only thing is, they are not making them in sedan form in 2010. My 2009 in Imperial Blue is one of less than 100 made. But it already has 37k miles on it.
Great commuter car that can whip some bigger car's a$$es....