They must not be very accurate then.
Maybe the cv they used had the 355 gears or something. My 2.73 gears and fully loaded truck with 3 suitcases, toys for the beach, box fan, 2 pedal bikes, etc… got 29mpg. I set the cruise on 70 and just left it there the majority of the way. I drove a little faster on the way home and it got about 26mpg. Think whatever you want, I know how to calculate gas mileage and know what my car got.
and BTW, that link you posted had the fuel type being used as CNG. I bet the gas mileage of “gas” is better than “Natural Gas”.