Successful trip from San Francisco Bay Area to Tahoe City last night in an early-vintage (VIN 002009) Model X 90D. These were under harder than normal conditions: 5 people (2 adults, 3 mid-size kids), new 20" snow tires (the ones Tesla sells). Normal amount of cargo for 5 people. Yakima Swingdaddy hitch rack + Yakima HitchSki attached to the trailer hitch (no cargo on it, just transporting the rack itself). Temperatures ranging from mid-50s Fahrenheit to a low of 32 degrees at the summit (elevation 7,200 feet). No weather to speak of, though it did start snowing a few hours after our arrival. Following are the interesting data points. Start San Mateo, CA. End Tahoe City, CA. Typical I-80 route. I normally drive speed limit + 7, and use Autopilot whenever it's available. At trip start, all-time mileage was 8,799, 359 Wh/mi. At trip end, 9,037 miles, 362 Wh/mi. Total trip: 238.2 miles, 486 Wh/mi. Started trip with charge at halfway through trip range (95% or so). Ended with about 32 indicated remaining miles (probably about 12%). One stop at Rocklin Supercharger, charged 11 mins more than the point where we got the "enough to continue your trip" notification. I recall it was about 220 remaining miles. Unfortunately I didn't note the Wh/mi at Rocklin or the top of the mountain, but I know that that leg hovered in the 600-680 Wh/mi range. I dialed down to speed limit + 0 (65mph) because the estimated range remaining was 25% at Rocklin but steadily dipped as we started up the hill. It stabilized around 16% when I reduced speed, but as it got colder it began dipping again, finally getting to 11% at the summit. I also switched to range mode when I slowed down. Interior temperature was set to 70 degrees. We turned on the defroster around 5,000 feet elevation and left it on for the rest of the trip. We didn't use the seat heaters. We didn't feel stressed-out enough to stop at the Truckee Supercharger. My wife did ask about it, but she agreed that we still had enough options left at that point that it wasn't worth the trouble. There was absolutely no traffic from Rocklin to Tahoe City. As I say, I consider this a successful trip. However, I did have to take precautions (range mode, 65mph, and a solid charge at the bottom of the hill) that I could see a newbie not knowing enough to undertake. And had there been stop-and-go traffic up the hill (as there often is on ski weekends), or snow/rain that likely would have substantially reduced our aerodynamics, we would have had less margin for error. I can't decide whether it would be a good idea to have one more Supercharger in between Rocklin and Truckee. On this trip, I probably would have stopped there for 15 minutes that I didn't actually need, which means that every other owner would probably do the same, which would mean that we'd be rate-limited to (60 / 15) x 8 = 32 Teslas per hour going to Tahoe North Shore. However, for days with traffic, having that SC option might make the difference between people arriving and people getting stuck. So it would have to be an "only if you really need it" Supercharger, which is a pipe dream.