Slant 6 Gas Mileage
The car you have ought to be getting 22-24 mpg on the road and a bit less in town. What rear gear ratio do you you have? That might make it a bit lower but not much.
No engine has that kind of internal drag even when first started to drop that kinda mileage. It hasa to be carb or really bad timing or somethign of that nature...I am betting the carb is way out. The choke sticking on would do it.
Real mileage on the '76 Dart Lite that I drove over 100k miles was 28 mpg highway at 70 mph; it would get 29 mpg in the midwest. It had the 4 spd OD trannie and around 3.0 rear gear. All stock.