I agree, the Vulcan 900's get great gas mileage! I usually get between 45-50mpg on a tank; once in awhile it'll dip down to 40mpg when I'm rolling on the throttle way too much. I have a friend who has a Suzuki Boulevard M50 and he's constantly stopping to fill it up. Besides only having a 4+ gallon tank, I don't think he gets great mileage either. All I know is I always ask him if he has a full tank before we head out.
Rode to Mount Lemmon on Sunday afternoon and just filled up yesterday. My trip odometer was at 187 miles and the low fuel light STILL hadn't come on yet. I put 3.4gal in the tank and I'm no math major but that means I still had 1.9gal left in the tank. That tank worked out awesome. Averaged out to 54.2mpg on that particular tank.