Tesla would *never* want to use ECE R85 because if they did, they'd have to start with the maximum power the P85D can make now, 557hp (minus some percentage for conversion losses before hitting the motor shaft) and then lose a ton more power.
You're either really bad at interpreting the test criteria or you've intentionally misconstrued this document:
"The electric drive train shall be equipped as specified in Annex 6 to thisRegulation. The electric drive train shall be supplied from a DC voltagesource with a maximum voltage drop of 5 per cent depending on time andcurrent (periods of less than 10 seconds excluded). "
I asked an EE upstairs what this meant just to confirm my own interpretation. What this means is that the DC power source may NOT drop in voltage more than 5% during the test. It means you can only draw as much current from the drivetrain battery as to not cause a voltage drop of more than 5%. The 10 second exclusion is there to keep the entire test from being thrown out if the voltage drops by say 5.1% for a few seconds.
I don't see how necessarily that is inconsistent with my interpretation. The document doesn't specify using standard equipment or a battery for the test (it says "Standard-production equipment" for every line except for DC voltage source). Correct me if I'm wrong about this. So they throw out results from sag of 5% or more, but then they don't say what power supply to use. The other point is they don't limit what test voltage the manufacturer uses (for example minimum, nominal, or peak voltage of battery pack).
http://www.unece.org/fileadmin/DAM/trans/main/wp29/wp29regs/2013/R085r1e.pdf
I think the difference is I'm working from Tesla's data to try to find out what standard they may have used to come up with "motor power" numbers. You are more concerned about what they
should have used or what would fit common sense for a consumer's assumptions for the phrase "motor power".
One thing I noticed and still remains consistent is the "motor power" are the same for cars with the same motor/inverter combinations, regardless of battery capability. S60/S70 same as S85, S60D/S70D same as S85D. This can't simply be a typo because it has remained true for every revision of the motor power numbers (it's still true today if you look at Tesla's site right now).
Your interpretation that "motor power" = power output at motor shaft considering the whole system, does not match with that. If that was what "motor power" is, S60/S70 should be proportionately lower than S85, and S60D/S70D should be proportionately lower than S85D, given the lower battery voltage (which is reflected in lower advertised system power).
If there was a standard that involves a power supply rather than a battery (as ECE R85 appears to be to me, although maybe I'm wrong about this), that would be a possible cause.
The other guess was what I suggested before, Tesla simply is advertising the maximum that they determined to be possible out of the motor/inverter in preparation of future upgrades to battery (and talk about move from 691hp to 762hp for P85D does not negate this, since Tesla can find out later they have underrated their equipment). This was also what David Noland said it was on the same day the "motor power" numbers came out, and this was not even in context of P85D, just the "motor power" numbers in general. The example he gave was he upgraded his 60kWh battery to 85kWh and all he had to do to get the same power at the motors as a S85 was a firmware update after that.
http://www.greencarreports.com/news...ower-numbers-for-tesla-model-s-whats-the-deal