I think Tesla's description of the slider helps keep it simple by encouraging owners to charge to a level that gives enough range for daily use while...
Keep in mind some of the "vampire loss" is self-discharge of the cells, which is a fact of life with LiOn batteries even if the current draw is zero....
For regular consumers I'm sure the slider will still default to the equivalent of a Standard charge and most people will just set it and forget it. ...
It was a very smooth trip, I'm relaxing in Old Montreal now enjoying a nice 23C spring day. I made a two hour stop for breakfast at the Best Western...