A short while ago, there was a discussion in one of the threads regarding the calculation of the "Rated Range" number that appears on the speedometer. I can't find the thread, so I am starting a new one.
The issue, in brief, was whether driving style affects rated range. Here is the text of an email message I sent to Ownership:
I wonder if you could settle an argument? In forum discussions, some people claim (and have been told by Tesla reps) that the "Rated Range" number that appears on the speedometer is partly determined by the way the vehicle has been driven recently. Others claim that the number is based on the battery's state of charge and a fixed energy consumption rate of approximately 308 watt-hours/mile. Still others claim that the number is based on state of charge, a fixed consumption rate, and certain other variables such as battery temperature -- but not driving style.
Could you please clarify how this number is derived? If you are uncertain, could you please find out from someone who knows?
My own personal view is that Rated Range WAS based on a fixed consumption rate prior to software version 4.3, but now includes other parameters such as battery temperature, but that driving style does not affect the way that the number is computed (although driving style obviously affects energy consumption, and hence the number of rated miles remaining at any given time). It would be nice to get an authoritative answer.
Thanks for any information you can provide.
Here is the answer I received:
Thank you for reaching out to us at Tesla Motors, and for patiently awaiting a response from us. I was delighted to get a clear reply from our powertrain systems architect. He states, with regard to how Rated Range is calculated:
Rated range = the car’s estimate of remaining energy / a fixed whpm. The fixed whpm is different for different vehicles (85kWh / 60kWh) and in different markets based on the regulatory test for that vehicle in that market.
Further information he would not elaborate on, but I hope this aids in ending the discrepancy regarding how we achieve your range predictions.
As always, please reach out to us again if there is anymore hash you need settling.
This is actually a simpler calculation than I had thought, although I had not anticipated that TM would use a different fixed whpm for each market. It does not explain why the relationship between rated miles used and whpm (as determined by the trip meter) seems to vary for a single vehicle. In any event, it does not appear that rated range is at all based on driving style.
Since it took about a week for Peter to get back to me on this question, I assume he got his answer from a fairly authoritative source.