Not to alarm you, but the highest price avgas in the U.S. recently topped $8, although the average hovers closer to the mid-5s. Long before this distressing development, a reader wrote with this suggestion: "You know, you really should look at the fuel economy of various airplanes. I’m beginning to wonder if there’s a big enough mileage difference to make it worth looking at something else."

Answer: We can, we have and there is. A certain class of owner—OK, the cheap screws—have always considered fuel efficiency above all else, either because they don’t have to carry much in the airplane or they don’t want or need to go fast. Of such…