With my Comp-G last time I did a little road trip I had 28-30mpg the whole trip(About 300 miles with about 100 of hills.). Gets about 20-24mpg city driving with a careful foot.
My L67 + 3.29 GT gets about 26-28mpg, but it's heavier. (Hitch, two subs, all my tools were often in my trunk.)