Had a 93 Dakota 4x4 with a v6 in it. I remember like 16-17 mpg in it. Friend had a v8 2wd Dakota that got 18 mpg. Both were more around town type of driving.
In my opinion with the mpg being so close the v6 is a waste of time.
Now newer ho 3.5 is a different story. The 3.5 moved out tank of a magnum along pretty damn good. Best we got cruising at about 50mph on the cruise control through va was 24mpg. That thing was just under 4000 pounds though. Drop 800 pounds like an early a that motor may be a good all around set up.