I understand your point but I still don't believe something is being "held back", you can de-cat a modern car and tune it to cruise at 17:1 AFR and pick up a bunch of fuel economy. I also know modern Corvettes are rated for almost 30 MPG highway so there's something with similar weight and engine size to your car getting that good of fuel economy. Your 32 MPG claim is pretty lofty as well, I don't think you're lying more just a miscalculation or something. Hard for me to believe but even if it is true nobody else has ever come close to that without a LOT of work. I'd almost say some of it was luck with your overall combo, not many others getting anywhere near that even in old Mopars that are purpose-built for gas mileage especially not with a 360. I remember a while back on Mofarts there was a guy with an A-body Barracuda who built a 318 purely for maximum gas mileage (with OD manual trans and well-matched gearing) and I think he just about broke 30 MPG.