Since the release of 6.1 I use the show battery percentage option instead of rated miles. I have MS60 (19") I purchased in January 2013 with almost 25k miles. On a recent trip to Tahoe, I watched the kWh used and compared that to battery percentage used (this avoids converting to/from rated miles since that is affected by driving conditions and speed). My basic observation: The car went from 100% to 50% SoC (while driving) but showed only 27.1kWh used. Using simple math: 27.1kWh / 50% = 54.2kWh max capacity of the battery. This assumes that the percentage indicators and kWh used are both correct, for some form of 'correct'. With that in mind, possible conclusions are: My battery lost nearly 10% of its capacity in 2 years (90.3%) The battery needs "rebalancing" Either the percentage or kWh indicators are not truly accurate Does driving up/down hill throw one of these measurements off? I need to go from 100% to 0% to get a real measurement I believe rated miles assumes 300Wh/Mi. Before 6.1 I would have to drive 275Wh/Mi to maintain parity between actual miles and rated.(I admit I haven't check this since 6.1, but that is my recollection beforehand). Given that 275/300 = 91%, that is somewhat consistent with my observation above. I plan on bringing this up with Tesla for my next service (next month). Any thoughts on this? Is this normal degradation for a 60? Or am I assuming too much?