Those tests of aluminum versus carbon fiber wheels are interesting, particularly the coast down.
In the Bosch Automotive handbook they give the equations for finding tire rolling resistance and aerodynamic Cd by coasting down from 60 mph.
Others have written that it is better to find these two values by coasting down two different grade hills at "terminal velocity"
because this is a steady speed test,
And rotating mass like wheels, driveshafts, gears, etc,
cannot add or subtract flywheel rotational energy
to skew the measurements.
The Car&Driver tests show that 20 lbs of wheel weight can indeed be measured by common stopwatch or ruler.
I've got a similar set of equations and spreadsheets. Stuff varying from how much horsepower it takes to drive a vehicle at X speed, Y grade, and Z size. I've also got the set of equations for a similar test that you measured by doing a coast down test.
