I'm not sure what would be useful other than the estimated range if you want to know the estimated range. I can't picture pulling out a calculator and doing my own calculations instead of trusting the provided tools.
Mental calculations are often adequate. For example, if I ask the planner to lay in a route to the Joyce Kilmer SC (Yelp review: "I think that I shall never see a place so lovely to stop and pee") it tells me that it is 197 miles from here and that starting at 90% charge I can expect to have 8% left when I arrive. That's 82% of my battery. I should be able to go about 3 miles on 1% of the battery per the EPA range of 295 for the car so the 197 miles should cost me 66%. 82% is 12% more than that and 12/66 is a bit less than 0.2 so the planner is telling me that I need about 20% more i.e. that I can expect about 80% efficiency. Looking at Stats data I see that this is about what the average X driver gets.
The planner has taken into account the terrain and the speed limits along the route. You can see, though the resolution is not adequate for great detail, places where the projected utilization curve goes a bit flatter or a bit steeper than the trend. These are places where you will be going down hill or up hill or expected to be driving faster or slower.
As you set out your actual history will be displayed to you and you will be able to see, graphically, whether you are doing better or worse than the plan indicates. And it also shows, based on what it knows about the rest of the route (terrain, speed limits) its projection for the rest of the trip.
It doesn't take future conditions into account.
Hmmm... then it is pretty useless, but I'm pretty sure you are wrong. Everyone who had encouraged me to forget the range indicator on the dash display said the navigator estimate DOES take into account the known factors of the remaining trip. Not sure what you base your claim on.
Based on the fact that it cannot possibly know that you will (prudently) slow down if your actual history line dips below the original projection curve or speed up if it goes above (the prudent driver would bank it especially if the estimate at destination were 5% remaining), nor whether the wind will come up or shift direction nor whether you will encounter a traffic jam nor whether it will start to rain or snow nor whether you will have to drive on gravel or dirt.
You seem to be going on about irrelevant issues in this case since the various conditions were good. There was a slight breeze, but nothing to consider and the road was dry on a warm day.
Clearly the relevant conditions weren't good because if they were you wouldn't have observed what you did. You did not have a failure of the car's navigation software. The failure was on the part of the driver to understand what the displays are telling him and what the relevant factors determining range are. Also, the decision to arrive at a destination with 5% charge in a place where alternatives are sparse without having thoroughly checked out the alternatives is hardly prudent.
I'm a gear head and am not bothered too much learning the intricate details..
That's exactly what you need to do.
I can't imagine what the typical person would do with the range issues presented by this car.
Until there are half a dozen reliable chargers in every hamlet, village and and town (i.e. until the chargers are as dense as gas stations) these cars are not for the typical person. Certainly my wife can run errands with the car around town but I could never expect her to begin to understand how the energy utilization curves work. Some people just do not have the particular skill sets required. Perhaps you are one of those people. I've noticed that you make a lot of posts about failures of the navigation system which, upon analysis, turn out not to be failures at all. Thousands of other drivers find it more than adequate.
How do you activate Teslawinds in the car?
Go to their website and follow the instructions for obtaining keys for the two services that allow access to the winds and elevation data. Follow those instructions exactly. In once case you must not only obtain the key by activate it. Now go to the car. Navigate to the TeslaWinds site and enter the keys. This can be a big pain because one of them is very long (20? hex characters) and they don't always take on the first attempt. Keep trying. You may have to come back and try another day but don't give up. Eventually you will succeed. When you do you are taken to a URL which contains your keys. Bookmark this.