Cᵣᵣ ranges from 0 to 10%, default is 0.7%. If using the AutoTerrain feature, assume a baseline value for smooth terrain (lower limit), as the app will generally increase the coefficient on rougher terrain.
To save battery and data, only one elevation point will be acquired from the Internet when you start tracking a new track. This is enough for the rest of the track to have a more accurate altitude baseline.