I know what you mean about challenges of getting an accurate measure, I rarely top back off and measure time accurately while out boating. Additionally consumption varies significantly with rpms and I typically am varying rpms over the boating trip. Addtional, performance varies with weight (people or fuel) and weather conditions. With all this said, your numbers are right in line with my experience 7-8 gallons per hour at typical cruising speeds. I have a 2001 Monterey 262, so I was interested to compare your experience. I thought I might be underestimating because fellow boaters with similar sized Sea Rays (similar engine) in our boating club where saying they consume more fuel. I checked the weight and the Monterey is lighter perhaps more effecient hull design as well? My Monterey gets up onto plane quicker and easier.