21 mpg?!?

With my 67 Ranchero with a 289 I was getting around 18-20mpg. I haven't tested the mpg in the Dart with the sl6 since it has been in varying states of work since we got it. Pretty sure the mileage is decent though. Needed gas when we bought it and I put about $40 in the tank (around 9 gallons I think) and we put on a lot of miles before I had to fill it.