I have been playing with my new to me 99 xb2003 Allison and have just put a smartcraft tach on which allows me to measure fuel flow.

I can easily check my boats mileage and so far its pretty good. At 60 mph I am burning 10.3 gallons or 5.82 mpg. That is about 2 1/2 mpg better than most full sized bass boats.

I am still propping the boat and am waiting to go up in prop size as my current 26p performer prop is running into the limiter. I think I will do over 6 mpg but I'll wait and see.

I am very happy. I think that more boat companies will have to start building more fuel efficient boats in the future but this boat is there now. Its a 20+ foot boat and capable of mid 70 mph with its 150.

The Allison is a very efficient hull, I got very good range from both the 200 pro max and even the 280 offshore I ran on mine.

However, the amount of driver input required to run that boat makes it still an "enthusiasts" boat at best.

Allison1, what are your opinions on your 518 ? I take it you dont like it? Is it for sale?

I changed boats after many years of looking from the outside at Allison boats. My truck is the most efficient one I could find, 20 mpg+ hwy and 17(now 18w/Allison)pulling my boat. Its a Dodge diesel.
My wife drives a VW jetta diesel and averages 44mpg driving in traffic and that car has seen a high of 57mpg on a long trip.
My new boat is just the next step. I like to see what I can do for efficiecy.

My Ranger is for sale. It is a good fishing boat. It is efficient but not compared to the Allison. The motor has been flawless with a tuneup once a year and had a new lower unit a couple years ago. The new lower unit is also the newer version of torquemaster that has low water pickups.
The boat itself had a weak transom that was replaced by Ranger three ? years ago. You can't tell it has been touched as they made and put in a whole new transom. Other than some gel coat cracks which are not bad,the boat is good.

the 2 things all men lie about is the size of their Johnson and their gas milage

I love the 17 year revival of this post but just wanna throw in that I love my XB2003. Can't bear to get rid of it even with new Allisons over here at the shop. I've put at least a dozen motors on it over the years, but had a 250xs on it 2 weekends ago on Toledo, I managed 7.2 mpg at just over 30mph. Of course that was just barely cruising but, fuel mileage is awesome in an 03. Very neat all around boat.

I had a 97 xb2003 with a 225 Johnson Going off gps mileage vans fuel used, I would get around 4 mpg. Extremely enjoyable to drive.

had several ally's/bullet's over tha years but hard ta get any milage with any motor with "both" feet on tha floor!!!