EVtripplanner gives you an estimated consumption over user defined routes and speeds. It was pretty spot on for the S but not it's constantly showing too little consumption for the X. (I've compared it with actual performance from teslafi)They used to have a little tool on the website (at least for the Model S) where you could estimate range based on battery size, speed and cabin temperature. I can't find it now
Interestingly the consumption predictor built into the X is very good after I've driven a few miles. It always starts off underestimating consumption but then quickly adjusts.