I must have a bad tune, only avg 10-12mpg around town. Mild 340, auto with 3.73 gears.
In the process of putting in a 518 tranny, but this will only help the hwy numbers, which I have no idea what that is, I'm guessing 15mpg?
Doing it to bring the RPMs down, it's teeth jarring to "cruise" at 3500-4000 rpm.