I can't remember. Did California cars have lean burn that year? In any case, it could be your carb needs a rebuild or a new (not remanufactured) one. Check out the ignition system real good, even looking at the timing chain. I know you said its low miles, but 318's are good for wearing out there timing chains for some reason. Catalitic converter? Could be plugged. For reference, my 5th Avenue gets around 20 mpg with a Eddy Performer and 1406 600cfm 4bbl and full 2.5" exhaust. Those engines like to breath a bit, and every little bit helps. 12mpg isn't bad around town, but not on the open road. But than again, in California, unless your doing 80 your getting run over, it was true even 20 years ago when I lived in the Bay Area. Meaning, if your keeping up with traffic, your milage will drop. Around here in Texas, most speed limits are 70-75, so speeds up to 80-85 are ok as long as your not driving like an idiot. I'm lucky if I get 15 at those speeds.
