I have a cobalt . . 2005 2.2 . . . i had a 99 cavalier 2.2 . .. and i think they started the new ecotecs in the 2003 cavaliers and sunfires (which are the same thing) ive been told that the difference between the 05 cobalt engine and the 04 cavalier engine is fuel injection . . like how its ported . . . if i had to go back i would have kept my 99 cavalier . . . over my cobalt . . neitehr is a race car (no S*it) but i sold my cavalier in 2005, with 205, 000 miles on it . . NEVER had a problem . . just wear and tear isues and i drive cars hard). I just saw someone driving it a week ago LOL. I dont know how they drive it . . or how many miles it has now . . but i was kinda impressed and regretful heh.
BUt i dont know what year sunfire youre talking about . . . i know now pontiac has a G5 which is a cobalt . . basically liek the cavy - Sunfire.
THough my cobalt is nicer and quicker then my old cavy . . my cavalier seemed to be *tougher* than the cobalt. and more simple to diagnose and work on
so hindsite and experience driving both . . i miss my old standby lol
so yeah . . .