Small block mileage

I know I will likely take some heat for posting this but chrysler had a decent idea in theory with the lean burn system. I could knock down 24 mpg on the highway and average a bit over 20mpg in my 79 diplomat coupe with the 318. I didn't go anywhere quick though with the 2.2 rear end. That, the lean burn, and the lockup torque converter made a difference and sipped gas.