By who, not by me. Nor my friends either. All my cars were great highway mpg for what they were. 170 around 30 mpg, 273 around 25 mpg, 340 about 20 mpg, 383 about 18 mpg. All trucks stink for mpg, too much frontal area and the tailgate acts as a parachute besides. Try driving with the tailgate down, instant +2 mpg.
The 225 in my duster got fair mileage. Some people have luck with a mopar getting good mileage. Mine never really did. I've known alot of people over the years that had a 318 in both cars and trucks and the mileage isn't there.