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Letter To Elon Musk Regarding P85D Horsepower – Discussion Thread

Discussion in 'Model S: Driving Dynamics' started by Andyw2100, Aug 20, 2015.

  1. ecarfan

    ecarfan Well-Known Member

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    Agreed. Typical journalistic hyperbole, and a very unbalanced article. You know, like the idea that the Model S has a massive number of "drivetrain failures" when in fact many were cases of a noise that was fixed by securing a loose cable, and Consumer Reports data on the Model S shows that less than 1% of owners have reported drivetrain problems.
     
  2. joer00

    joer00 Member

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    The update makes it 20 % faster at high speeds, currently the P85D has about 20% less power than advertised, surprise surprise !!

    And what you describe is EXACTLY the problem. I just had a P85+ loaner and was shocked how fast it was. Above 30 mph I did not feel any difference. With 691 HP the P85D will not be as fast as an ICE with PDK, but it will be MUCH FASTER than a P85 or 85D.

    So I think all points in the letter are 100 % valid.
     
  3. ProSkeptic

    ProSkeptic Member

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    #83 ProSkeptic, Aug 21, 2015
    Last edited: Aug 21, 2015
    Assuming that Elon's above statement is correct (and considering that it's corroborated by Consumer Reports' acceleration test versus the Charger Hellcat, I'd trust it to be correct) the P85D is delivering about 300 kW to the pavement (5,000 lb car accelerating at 1 g at a speed of 30 mph) with an elapsed time of 1.36 s. This is a true theoretical 0-30 time, so don't bother trying to apply rollout or any other such 'corrections' to it. Extrapolating this power rate through a speed of 60 mph gives a Δt of 2.02 s from 30 to 60, for a final 0-60 time of 3.38 s. Okay, so maybe Elon was holding back a little bit on the '0-30' figure, or maybe the acceleration is actually a shade over 1.0 g - it doesn't much matter since the elapsed time number from straight mechanics doesn't account for aerodynamic drag, or the non-instantaneous ramp-up in acceleration from 0 to 1 g. So, in short, I'd stand pretty firmly behind the 300 kW that's actually being delivered through the tires.

    What does this imply for the acceleration of the P90DL? All else being equal, the power delivered to the pavement isn't going to improve beyond the improvement in current delivered from the battery, and that amounts to 15/13 of the current being delivered in the P85D. So the P90DL will actually be traction limited to only 35 mph instead of the claimed 60, and its 0-60 time will come out in the ballpark of 3.13 s.

    Until and unless Tesla can produce real test conditions and parameters to back up their acceleration numbers, I'll stand behind what mechanics tells me.
     
  4. Whity Whiteman

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    I drive the P85D and I am a huge fan of Tesla an d Elon. BUT, they advertised it with 700 HP in Europe. On the german Autobahn the limiter kicks in after one minute full throttle!!! You than get the half of the power (240KW). It is okay, but not the real deal. So the fix isn't about loudicrous, it is about the limiter. If they change the contactors and the fuse for existing custumers, then they get, what was announced! The Lude-Mode on top can be charged with whatever! But it feels wrong, when you drive on highway speeds.. that's not the crazy insane car.. it is more like a mediumbig E-Class if you floor it...
     
  5. rns-e

    rns-e Member

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    3.13s with Ludicrous will meet the advertised numbers for the P85D - at least in Europe, where that would be 3.3s 0-100km/h
     
  6. ProSkeptic

    ProSkeptic Member

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    Thus lending credence to those who believe that the -L upgrade was what was originally intended as the OTA upgrade to the P85D...
     
  7. Xenoilphobe

    Xenoilphobe Active Member

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    Evan is right - my censorship statement deals with another forum - not this specific thread. Snippiness deserved. Mea Culpa Evan! No more bourbon and posts a 1AM! Peace!
     
  8. ProSkeptic

    ProSkeptic Member

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    I'll thank you to not disparage bourbon.
     
  9. Olle

    Olle Member

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    #89 Olle, Aug 21, 2015
    Last edited: Aug 21, 2015
    The letter says that it wants to help Tesla from negative press, before it happens.

    If it weren't for the extortion part in the letter I think that that it is good and might help Tesla think about honesty in advertising. As the letter stands now it would make juicy news to feed the short sellers and everyone else standing to lose from Teslas success.

    The press loves conflicts but doesn't care about somebody trying to help somebody else.
     
  10. Hookmaker

    Hookmaker Member

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    I signed your letter via PM, Andy.

    See stock is down 4,7% today - The letter?....;-) If I were Elon, I'd get to the keyboard real quick (I'm sorry to say).
     
  11. bonnie

    bonnie Oil is for sissies.

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    That's been a bit of an issue for me - if people truly want to prevent negative press, an open letter in a very public forum doesn't seem a good way to accomplish that.
     
  12. omarsultan

    omarsultan Active Member

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    To be honest, if I were Tesla, I would offer all of you a buyback and bid you farewell. For a company that prides itself on continually improving the car, providing free upgrades, espcially when Ludicrous mode is a paid upgrade on new orders, is a lousy precedent to set.

    The irony here is that of all the "super cars" out the, the P85D is the only car where folks not named @lolachampcar have a chance in heck of getting close to manufacturer specs, but the reward for putting that kind of performance within reach of mere mortals is simply opening up another avenue for criticism.
     
  13. Laserbrain

    Laserbrain Member

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    Do you think 100% of the owners are active in this forum? Looks to me like the rolling eyes are more appropriate for the people who signed the letter.

    However. In my country, selling a roundabout 500 HP car as a 691 HP car, we have got a word for it. And it does not help that the car is still a great car. And super cool and everything. But I don't want to say it out loud. For legal reasons of course.

    But, I think going for a free Ludicrous upgrade would be wrong. First, I dont think the Ludicrous upgrade would deliver 691 HP either (maybe 600 HP), second it's just not appropriate. Look at the Mazda case: Because of false advertising Tesla should buy the P85Ds of unhappy customers back. And thats it. No free upgrades. But then you could get a cheaper 85D, which is in reality not much worse as a P85D. And happy P85D customers can keep their P85D. Pacem in terris.
     
  14. JohnSnowNW

    JohnSnowNW Active Member

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    As far as I'm concerned the metric being used to verify the numbers Tesla is quoting has yet to be proven worthwhile. Unless someone can tell me how Tesla arrived at the numbers quoted, and how that affects how they've "misrepresented" the performance of the vehicle, then much of this is nothing but whining...or if I want to be even more pessimistic an attempt to get a free upgrade.

    With that aside, the article is still taking liberties with the headline...and is exactly the reason why I take issue with people trying to make it seem like they're doing Tesla a favor with this.
     
  15. stopcrazypp

    stopcrazypp Well-Known Member

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    I've been trying to do find out how Tesla arrived at the 691hp "motor power" too. I spent a decent amount of time gathering a comprehensive list of motor power numbers and best estimate of REST API power numbers (power numbers measured from battery output). Long story short, the consistent thing is whenever there is a motor/inverter combination that is shared among models, the "motor power" number is the same (S60/S70 same as S85, S60D/S70D same as S85D). There are some changes to numbers from time to time, but if you look at numbers on the same page/time this has been consistent.

    I have arrived at two theories:
    1) "motor power" is the max capability Tesla has measured out of their motor/inverter combination installed in the car, regardless of battery capabilities (David Noland suggests that it illustrates the possible upgrade path with the car; in his case he upgraded his 60kWh pack to 85kWh and got more power out of his car/motors). Some have argued the increase from 470 rear+221 front motor power for the P85D to 503 rear+259 front motor power for the P90D L invalidates this theory. I don't think it does, given Tesla could have underrated the motor/inverters at the first go, or an older P85D may not have the same motor/inverters as a P90D L out of the factory today (we don't know yet that a retrofitted P85D L performs the same as a P90D L from the factory).
    2) "motor power" is measured with a power supply (not a factory equipped battery) attached to the drivetrain, thus not taking voltage sag into account (as I suspect ECE R85 is doing).
    http://www.teslamotorsclub.com/showthread.php/44691-P85D-691HP-should-have-an-asterisk-*-next-to-it-Up-to-691HP/page119?p=1115469#post1115469
    http://www.teslamotorsclub.com/showthread.php/51563-Calling-P85D-owners-world-wide-for-survey-and-complaint-letter/page36?p=1118587&viewfull=1#post1118587

    Of course, from my back and forth with P85D owners, I don't think they want to find out or understand what Tesla really means when they say "motor power". From their perspective, their interpretation of "691hp motor power" is 691hp at the motor shafts with the entire system taken into account. The other threads have determined that the P85D does not make 691hp at the motor shafts. Thus reality does not match that interpretation and they feel Tesla owes them the missing power. If there is another logical interpretation of the "motor power" then that would undermine their case and I don't think they are interested in finding that out. I think what they are not seeing is that it is possible for a statement to be factually true, but still be misleading to people.
     
  16. Andyw2100

    Andyw2100 Supporting Member

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    In retrospect, it looks like it wasn't.

    For months there have been many threads with extremely negative posts. There was a fairly recently started thread with "P85D" and "complaint letter" in the thread title, and the group that started that thread actually also started a website. The media didn't pick up on any of those things.

    Many people were suggesting writing to Tesla, to decrease the amount of discourse on the subject. People writing as individuals had not been receiving responses. So I thought, in hindsight perhaps now incorrectly, that writing a letter to Elon Musk, and having it signed by a bunch of forum members, would be a good idea. I purposely worded the letter to make it clear that we supported Tesla, and that we didn't think Tesla had intentionally misled us. If the media wanted to pick something to skewer Tesla with, they could have picked any number of threads here. In fact, unless I'm mistaken, in the ten months or so that I've been active on TMC, I think the only story before this one that was picked up by the media was the recent one about owners being upset about the supercharging letter. (I could be wrong about this.) It's certainly not as if any Tesla-negative thread is immediately newsworthy. I really did not expect this. I thought we'd gather signatures for a week or more, send the letter off, and then have to hope that it somehow made it to Elon Musk.

    Again, in retrospect perhaps I should have anticipated something like this. Unfortunately I did not.
     
  17. tezzla

    tezzla Member

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    Tesla/Elon had 5 months (since the 691hp thread) to clarify their position on the horsepower issue.
     
  18. bonnie

    bonnie Oil is for sissies.

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    I believe your intent was good. However, I do believe there is at least one on this forum actively contacting media about the matter & they used this in their quest. It pretty much wrote the story from the viewpoint of people signing, and then they just needed to slap some filler around it ... and done!
     
  19. Andyw2100

    Andyw2100 Supporting Member

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    I appreciate that.


    The headline was certainly misleading, and not really representative of the sentiments expressed in the letter. On the other hand, I do give that publication credit for at least printing the entire letter, which allows readers to make their own judgments on it (although it makes me look like an idiot, talking about going to Musk with the information, before the media gets wind of it), and also for providing at least a little bit of editorial content of their own that was positive. They did say, "These are all fans of Elon Musk and of the Tesla Motors Model S..."

    They also used an excerpt from the letter that was quite positive: “Every signer of this letter wants Tesla to continue to grow, to prosper, and to succeed in changing the world! We trust that with the information we have provided, you will come up with a solution that works for Tesla and for the affected customers.”


    I'm not by any means saying this was a good article. I'm just pointing out that it easily could have been worse.

    The headline really did misrepresent the letter.
     
  20. omarsultan

    omarsultan Active Member

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    I think this is more clear after the Ludicrous announcement as it provided a important data point that I don't think was public knowledge before--the max draw on the battery pack is 1300A. As we know its a 400V pack, 1300 A * 400 V = 520,000 W. Both Watts and horsepower are units of power, so the conversion is straightforward: 1 hp = 745.699872 W, so 520,000 W = 697 hp. We still have a 6hp discrepancy. My best guess is the max draw is not exactly 1300 A and there should also be some efficiency losses along the way, which could both contribute to the delta.
     

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