mileage. the harder i try the worse it gets...

yes, got 20 mpg in my 72 demon with a real worn out 318 that I pulled from my 67 Belvevere. That was on the interstate doing exactly 60 mph. This was back in the days when gas was gas (no alchohol). And I tuned and tuned that car. (still had the points!).
THis was on a trip from FL to NJ up I-95. BTW, it had a stromberg 2 bbl, single plane intake (factory!) a 727 and 8 3/4 with 2.94 gears. I could not believe it myself at the time! I remember wondering why the needle was not moving on the gauge;though it was broke or something. I think the cool air (Oct), and you know the thick air (low elevation)
and the constant and exact speed helped. That and the motor was seriously on the loose side (worn out, low friction I call it). I had ripped out the rear seat and stuffed all my belongings back there and packed up the trunk so, light weight of the demon had no effect on things. Oh well, those were the days.