[Bushwacker]

You'd get a more accurate result if you ran a full 6 gallon tank thru it, but 3 mpg is probably in the ball park. I averaged 2.8 mpg with my ancient 115 crossflow Evinrude over 6 trips to the Abaco's. This was running with a very heavy load, carrying 65-80 gallons of gas, a couple of coolers, dive gear and a couple of weeks worth of grocries.

30 mph is probably above your optimum cruise speed. I believe the "sweet spot" for the 20' hull is about 25 mph because that's where the hull hits minimum running angle. (Check out the Boating Magazine test of a 69 Seafari in the Literature section.) Of course the optimum cruise point for a given rig also depends on engine/prop characteristics as well. Optimum cruise on my 150 E-Tec seems to be at about 25 mph, with rpm between 3500-3800 rpm, depending on what prop and load I'm carrying. Instantaneous cruise MPG from the I-Command system (based on gps speedo and fuel flow from ECU map) varies from about 3.8 to 5.2, depending on load, prop and wind/sea conditions. One neat feature with the E-Tec is that if you're running low on gas and worried about running out, just slow down to hull speed (~ 5 mph), where it's running in the lean burn stratafied charge mode, and gets 8-12 mpg!