Sorry, Texas EV. Rated range for a new 90D Model S, is often found to be less than 285 miles:
This list took me about 20 seconds. I'm sure there are more.
"My P90DL showed 265 miles at 100% in September when I got it."
"My P90D charges up to 266"
"100 percent charge I only show 271 miles"
So unless they all have degraded batteries as well as mine, the rated wh/mi used for the calculations is probably pretty close to the 320 that was quoted to me. Perhaps the rated wh/mi used to calculate range was changed from some time ago when you got your information.
But that argument misses the point. The cars energy consumption display repeatedly shows an extrapolated useable battery capacity of about 72kwh. And the rated 100% range display is at or near that displayed on a new 90D. And that range is not achievable by any definition of ordinary driving.
The P90D has a different rated range than the 90D.