Firstly I must state that I absolutely love my MS, and this is my first post so seeing other people getting ripped apart in this forum i am hoping everyone will be gentle with me since it is my first time.
Not a complaint really but just a heads up to those who live in cold climes ... I planned a trip from my home up to Lambeau last weekend to try and enjoy what turned out to be a miserable game, and was surprised by the amount of degradation of range experienced in the 20 degree weather. I have made similar length trips in the summer/fall, and even longer without this problem. I had max charged my 85 overnight, ran a few errands first but left with at least a 250 mi range and arrived in the parking lot with 75 mi left. Google maps shows it at a 109 mi trip but that seems long based on how long it took, but even at that I was about 66 mi short. I did drive a little fast (low 70's) but had the heat set on 66 and was just playing AM radio. I was forced to find a charger to make it back post game and using plugshare and driving around a bit found a Tesla labeled charger at AMI, inc on the north side of town - thank you whoever you are! I was then stuck charging it for approx 3 hrs, and decided to try and make it back when the charge hit 129 mi - i assumed if i toned down the speed (60 mph) and set it to powersave i should make it (I think it is really closer to a 90 mi trip). However I only made it down to fabulous Sheboogie WI with the low batt warnings starting and 22 mi of range left, that was a 67 mi trip, again a significant degredation of range on the order of 40 mi. Keep in mind this is pretty much all "freeway" type driving. There was a Kwik Trip with a 120V plug, but in this weather that pretty much only keeps the batt warm. Fortunately my better half was able to fetch me, and i am still not there waiting.
Thankfully the service folks in Villa Park, IL (thanks Laura et al) were kind enough to divert a delivery truck in the area to pick it up and bring it back to me the next day. I think all agreed that level of degradation was not anticipated by anyone, therefore i wasn't just being dumb in my range expectations. The point of this story however, and the tech seemed to agree with me, is that if you are doing just highway driving in cold weather (20 degrees is frankly not even that cold up here in the hinterlands!) the battery seems to be doing double duty of staying warm and moving the car. There is very little regen happening to help the batt along, so if presented with this situation one should plan accorgingly - by my higher math skills based on the above example even somewhere in the vicinity of 65-70% of what the car tells you it can go to be conservative. Not sure if even colder temps would degrade even further? So if i could have a do over i would have just used my wife's hybrid, until they put some superchargers up my way.