21 mpg?!?

My first car was a 66 Slant 6 no option Coronet. It would get 25 mpg on long trips back in the day of 75 mph speeds. It had over 200k miles. Modifications included taller air cleaner, water injection, and CDI ignition I developed from scratch.

I sold it to buy my 66 273 Baarracuda, it has auto and ps. It still got 25 mpg. Now days low 20s. My experience suggests about 10% less mpg with 10% ethanol.