wow my car has less then 30,000 miles on it, and its bone stock 2004 ZX3 with MTX and i have been getting 30-32 for the last 3 months! and i drive it pretty hard, i shift in the 4-5k rpm range %95 of the time!
and im jsut using cheap costco gas! and some non syn blend oil(i want the rings to seat)
i think its cause im not to hard on the gas, and keep it in its power band whenever i acclerate, then i drop it to ~2k for cruzing (weather that be 35mph or 70mph)
the car was getting 28-29 when we first got it, but i think the engien is just getting done breaking in.
whats crazy still, is there is a hill i drag up every now and again ( foot all the way down!) and the thing still gets 30+ mpg, i really cant complain!
im almost scared to put a difrent intake and exhuast on it :P