I am looking at buying a mustang coupe between 1965-1968, and i was wondering what kind of gas mileage i can expect. I am looking to get one that has a 6 cylinder(200 straight six) with a manual transmission, and if I can, a single barrel carburetor. Im not looking for a racecar or a hotrod, I just love the classics. What kind of gas mileage could I expect out of this, and what could i do to improve it without spending a ton of money? I have heard claims that putting a few ounces of acetone in the gas tank helps...is this true? What about leaning out the jets of the carb? Any help appreciated.