Outboard fuel burn rates
 

Generalizations......
1. WOT outboard burns approx 10 percent HP so with a 200 HP burn about 20 gal per hr.
2. Cruise is approx half that burn so 10 gal p hr etc.

New - current outboard efficiency increased greatly improved from idle, trolling speed up to cruise speed. From the 2 stroke Etec to the newest 4 strokes, fuel burn rates reportedly cut in half from older carb and efis ......

Maybe or even likely electric outboards market position will grow and the energy cost evaluation continues.

I haven’t done any calculations but according to the fuel gauge I have been very satisfied with the fuel consumption on the Mercury Saltwater 225 which is a Yamaha F225 I love this motor on this boat

anyone have fuel burn numbers on a 1996 Johnson 200 Oceanrunner?
Running it on a 1975 V20 center console. Fuel burn seems excessive, but nothing in the water, so I don't think I am leaking anywhere

Like BG carbed 2 stroke 200 would be about 20 GPH, That is wide open

U should be getting.between 2 to 3 mpg, but there are a lot of variables in this equation

You should also see a speed of close to or at 50MPH, depending on your load and the water conditions. What size prop and what pitch do you have on your engine?