It would be interesting to see if this 2.75 miles a gallon in the 255 is sustained as the boat is used for cruising and has full fuel. There is no reason that the 175 should get 0.5 miles a gallon better than the boats with the 150's. I suspect that the 175 is using the same props. The 150's give light boat speeds in the high 40's.
The 2.2 miles per gallon which Matt refers to is what many of us have found over several thousand miles of cruising and seems to be the best we can get at 20 knots or so, with a boat which has fuel, water, supplies and gear for a few days on the water.
Of course, the question is always asked how was this average calculated? Was it off flow guages which have been calibrated? Or is it an average of a days run? If it was an average, what percent time was at low speeds? The Tom cat begins to get better mileage below 7 miles an hour, in calm water--if it is choppy, the mileage will decrease.
