Since most of mine have been daily driven at one time or another, I've kept track of the gas mileage....I only kept track on long trips with the '74.
'74 Coupe V6, stock ,4spd, 3.55 gears...16 - 18mpg.
same '74 w/ stock 2bbl 302, C4, 3.55 gears...16mpg freeway (unknown in town)
same '74 w/...