Best possible mileage?

My old 93 Dakota w od only got 18
I've had a few 318 Dakota's, the champ in mileage was the 93 on which I converted it to a 5 speed and added the 3rd pedal. I miss that truck!!!!!20 mpg without even trying, but that's not the only reason I miss it. I replaced that with a 92 318 Dakota (I wrecked the 93 way beyond repair) then later, my wife talked me out of fixing the trans at about 230k miles and I junked it. Another one I miss. Not quite as good on gas as the 93 but still never worse than any of the 3.9 Dakota's I have also had.(the best of which was the 90 with TBI not magnum) neither of my magnum 3.9s could ever Break 17. And were dogs on power, besides
Currently I have a 96 4wd 318 Dakota. This one is 3.91 gears rest were all 3.55. can get 17 if I'm nice to it in combo driving. Still no worse than any 3.8 and have V8 power to boot. All my 318 Dakota's have been club cabs. All my 3.9 ones except the 99 were reg cabs. The 99was club cab. I also have a 12 ram 1500 2wd reg cab Long bed . This is my 1st 4.7 ever. That one is doing 18-ish.
For mileage while the weather cooperates I have a Harley Sportster. Gets around 45-48.
Idk what my /6 truck will get, kinda anxious to find out soon as I get my new /6 swapped in and get it registered.