Who told you that? Some hater at the Fudger Forums?
The worst I've ever gotten was riding 105 mph for 200 miles directly into a 30 mph head wind. Got about 31-32.
Under normal circumstances 70-75 mph and light winds I would get 38 to 41.
However I recently installed an economy fuel map to my PC3. Now at a constant 70 mph on road trips I get 46 to 48 mpg.