I like my performance and ride before fuel milage. I used to think the same, and sometimes even compare with others at fuel stops. But for a difference of 2-4 mpg's, it isn't worth it. A very good friend asked me, "What was more important, enjoying the sport of snowmobiling, or arguing about mpg's?"
Now, to those that care more about mpg's....... Talked to my buddies who each own a new sdi, and they said 16-18mpg. They do a lot of trail riding, and this was all types of trail, but said boondocking they didn't know. just their .02