I have received my Model S in 03/2018, with the firmware 2018.12. The battery level at destination was outstanding, I always arrived very close to it. I upgraded from 2018.12 to 2018.26 recently (no updates in between, because the OTA updates had been left disabled when I received the car, which was fixed in a service center which immediately triggered update to 2018.26) Now, the battery consumption is always very overestimated by the GPS. For instance, on a trip starting at 80%, it will tell me that upon arrival I will be at 5%. After one hour or so, it raises to about 15%, and I arrive at about 20%. This is especially an issue when it tells me to do useless supercharger stops. It may tell me to do one while I arrive at destination at 15%, thus giving me a totally wrong estimation of the time to arrival. The other day, I did a long 600km trip with three possible supercharges at about 100km, 180km and 380km. The battery was 93% at the beginning. The GPS estimated I could not reach the third one with enough margin, so it told me to stop at 180km, which I reached with 57%. I was able to reach the one at 380km with 16% battery, which is more than enough in terms of safety margin, and a better strategy as the supercharge is much faster at low battery levels, thus requiring a super short charging time to give me the range to do the last 120km. While after one hour or so of driving it gives me a better estimation, just stopping the GPS and entering the destination again causes it to go back to the very bad initial estimation. This is super frustrating, I can't use anymore the GPS to know my time of arrival and plan charges efficiently. I have checked that I do a very consistent 200Wh/km (+/- 5) which is exactly the typical range estimate. All mentioned trips are on highway at a steady 120km/h speed.