Hi. We have a 1988, 36 Carver aft cabin and currently boat on Lake Michigan. She has 454s with 350 hp each. The best I ever got was close to 2 miles per gallon at around 8 to 9 miles per hour at 1,300 rpm (the lake was flat). I cruise at 2,600 rpm and get 18 miles per hour and burn approx 1 gallon per mile. If I have to get off the lake quickly, I can get 30 miles an hour at 3,600 rpm, but then my gpm is under 1/2 gallon (don't tell the wife). I also have VC 17 on my bottom. Hope this helps.