I have no intention of moving to South Dakota either. If we all started moving there, ken would have to move south to the middle of nowhere Nebraska.
My point about f.s.c. being based on the national average price of diesel fuel being a bonus for gas burners is the disparity between the national average price of diesel and gasoline. Today, according to AAA or AA on the wino-meter the average national price for regular gasoline is $3.47/gal. Diesel is $3.88/gal. I average just under 17 mpg in my gas Chevy. A 40 cent difference at the pump brings my fuel cost per mile much closer to OVM's Sprinter cost per mile.
I'm sure most carriers base their f.s.c. on diesel because the majority of their fleet burns diesel. It makes things much simpler.