i was directed to this site by someone on grassroots motor sports page. that is a great site with lots of eclectic stuff. any way i have a 1999 sunfire that had the 2200 four. it also has been "blessed" with the three speed auto. i have done some things in the name of performace that have lead to better FE. i have installed a header, that has made the biggest improvement to FE. i regularly get 500kms per tank now. i also have cleaned up the intake and added a open "k and n" style filter.
not the most desirable starting point but you have to work with what you got until you can get something different.