MPG experiment....1976 Dart Lite
UPDATE
I could not wait until this afternoon. I topped off at same station, same pump, with same routine. 54 miles on 2.97 gallons = 18.18 MPG.
Previous was 13.5 mpg.
Adjustments made between 13.5 and 18.18 was tire pressure, tires were under-inflated and the carb was rebuilt. Basic parts store rebuild kit, on a 1945 Holley.
Stock, this car had 6.95 x 14 tires, which converters to 25.3 OD if I understand correctly. Currently, tires are 235/60/15, which convert to 26.1 OD. 26.1 / 25.3 = 1.03 or 3% taller tires.
This changes the baseline to 13.9 MPG, and the current to 18.72 MPG.
Next up: Identify gear set, and fluid change in both differential and transmission. Who knows how much better it will shift and drive with new fluid.