I was wondering why I am getting quite widely different kWHr usage on my daily commute over HW 17 Santa Cruz, where the main variables are temperature and driving speed. I've seen variations between 280WHr/mile to 350WHr per mile (I have a 60kWHr battery). Since the speed mostly below 60mph, aerodynamic losses probably do not account for the whole variability. I took a look at the losses due to battery internal resistance, and came to the conclusion that losses due to (high) acceleration and hill climbing at different speeds are significant, accounting for about a 10% variation. If you are interested in the details you can follow the link to a google spreadsheet that shows an estimate of the effective battery efficiency at various output powers for all three battery sizes.