EV range is an elusive number. Stated maximum range is based on a set of assumed "average" conditions, and I have not seen any specs which state what these conditions are. A few actaul conditions affecting range are: speed and time driving at various speeds as in highway travel; variations and frequency of variations in speed as in stop and go driving; moderate or aggressive driving habits, terrain as in level, hilly or mountainous areas; wind direction and speed, ambient air temperature, need for heat or a/c, number of passengers and weight in the car.
For where I live in northern MN and where I need to drive, and usually both my wife and myself in the Tesla, I'm still learning at what "range" the Tesla actually has. Things which have a big impact for us are vehicle speed, wind velocity, and temperature. Neither my wife nor I are aggressive drivers, although we both enjoy the acceleration experience of the Tesla. And the terrain is pretty flat for most of our driving area.
Our typical long trip destination is 185 miles one way. This so far has been no issue with our Tesla in Spring, Summer and Fall driving, and we would finish this trip with about 110 miles +/- of range remaining. Total range about 295 miles. Our driving would be at posted speed limits, up to 70 mph.
But when we drove this the day before Thanksgiving a few days ago, with strong crosswinds, temperatures in the mid 20'sF, two dogs and luggage in the car, cabin temperature at 66F, and limiting our speed to 65mph, except where traffic flow required us to go faster, it appeared that we would exhaust our range at about 190 miles, so we stopped briefly at a Supercharger a short distance off our route to make sure we would arrive at our destination with sufficient range remaining to make the 10 mile trip to the Supercharger near out destination to get a full charge for the trip home.
This reduced winter range, at about 40%, even if more reduced in more extreme conditions, will not be a problem for us. We can leave home with a full charge, and we have four Tesla Superchargers located along the route to charge as needed.
The reduced range we experienced also was impacted by us installing winter tires on the Tesla. It would not surprise me if the added rolling resistance of those tires resulted in a 5-10% range reduction over the range we would have had with the (summer) tires provided on the Tesla. I'm a firm believer in winter tires for added safety, given our cold, icy and snowy condition in our MN winters.