Thought of another flaw in the calculator: CRR entered is supposed to be for the tires' resistance, but rolling resistance involves some drivetrain resistance as well (bearings, possible brake drag, CV/U joints, differential).
Determining your actual Crr experimentally and entering it would be best. See:
http://ecomodder.com/forum/showthrea...stance-62.html
and/or
http://ecomodder.com/forum/showthrea...mula-3737.html