Thanks for putting this together.
I put together this "Drag Estimator" for my HS supermileage team years ago. It is based off of the Empirical rolling resistance and wind resistance test given in the Bosch automotive handbook.
http://www.epulaski.k12.in.us/tech/s...ign/design.htm
For rolling resistance, this gives a constant coefficient and a v^2 coefficient.