Dunerunner, you can call my bluff. Hand over your chips.
With nearly every available performance mod, a lean tune, and a light foot, I made it almost all the way to the national meet on one tank. I had one tank where I broke 500, kept the rpms low, and all the driving was interstate. TJR calculated 22.7 mpg but I've calculated as high as 27mpg before, and several members have done the same with their scan tools. When filling up, I always use the same pump at the same station (#1 Shell intersection of Gay St. and Glenn).