Pretty sure the Performance models use a higher Wh/mile number for Rated Miles because of the large rear motor.
For some reason on my P90DL I thought it was 340 Wh/mile but my memory could be off. I used the fueleconomy.gov site to see the city/highway/combined MPGe which you can convert to Wh/Mile. Here is what I see for the 2 vehicles variants I owned. '16 90D, '16 P90D, '17 100D, '17 P100D Range of various MPGes was 81 to 94. MPGe to Wh/mi conversion tables with examples and formulas
I was getting battery capacity and rated-watt-hour-per-mile values from here: Calculate usable battery capacity based on rated miles values
2016 MX 75D (August build), 65,000 miles: 90% SOC rated miles = 198 miles My 100% SOC miles dropped to 220 miles within the first 8 to 12 months, and has remained constant since then. Degradation on my 2018 M3 is actually worse than the older MX.
I believe the EPA numbers include charging losses, so they're going to show a higher Wh/mile than the vehicle will use for an internal calculation.