Smallblock efficiency or How to have your cake and eat it too

I used to drive my 68 barracuda with a 318 4 bbl and got 17.75 mpg with a 2.76 axle....

My dad had a bone stock 76 Charger with a 360 that got 20 MPG and had a 25 gallon tank = 500 mile range...

18 - 20 MPG is not out of the question...