There are soooo many variables that contribute to the overall efficiency, and therefore the range you will get, out of the battery/vehicle. But one thing that is fairly constant in any calculation is that the faster you go, the greater your range will drop.
It's also not exactly linear either. 20 vs 35 mph will not see much difference in efficiency. But a 60 vs 75 mph comparison will. If you slow down to around 62-65 mph, and if the temp increased by 5-7 degrees you may not see it dip as much... but then again, who wants to go friggin slow in a Tesla!?