1973 Dart Swinger Gas mileage

17 is pretty good. If it was mine, I would put an Edelbrock performer and an Edelbrock 500 on it. A 4 barrell will get better mileage as long as you're conservative with your right foot. A set of headers will also help with mileage and power as well. Also, as mentioned, you can try some higher gears. On the highway, a 3.23 gear with stock, short tires will burn some gas.

First thing I would do though, before dropping a dime would be to make sure your present combination is in optimum tune. That could pick up the mileage a bit right there.