Wow, phleas is putting down some great numbers!
Our vehicles are just a little different. Mine was the last year of the 2200 motor, which is a 2.2L 8 valve pushrod. He has the 2.2L 16v DOHC Ecotec. Both are rated 33mpg highway by 2007 ratings.
Unfortunately, I'm not going to be able to put down all highway tanks like he does. My work commute is 3.2mi of city driving on a cold engine.
I'd be interested to know which mods got him that huge increase. I'm considering fiberglassing a belly pan as well.