I'll bet he never went over 40 miles per to get that number.
I drove my g.f's 89 Corvette from here to Milwaukee on the interstate, never had it past 135 but spent most of the time between 60 and 80. Got a lousy 26.1 for the trip.
I did get some strange looks at the toll booths on the way back. I went to a swap meet and the whole passenger area and under the hatch was loaded with treasure, like a pair of heads, set of headers, intake and carb and other misc junk.
Who needs an econo box......