Letter To Elon Musk Regarding P85D Horsepower – Discussion Thread

[Andyw2100]

It's un-surprising that you ignore the facts to fit your viewpoint. CR doesn't do the roll out, they specifically mention this. Several other automotive publications have gotten the advertised specs, and one has gotten better.

Of course, you'll just ignore this.

I recognize that CR tested without 1 foot roll out. I actually thought that they should have pointed out the difference in testing methodology in their video, rather than just saying that Tesla came up short.

On the other hand, I do think Tesla should have indicated somewhere on the P85D specs that they were now using 1 foot roll out, since they hadn't previously. Anyone shopping the P85D 0-60 time against other Tesla models' 0-60 times saw inflated differences due to the fact that 1 foot roll out was used to obtain the P85D time but wasn't used to obtain the other models' times.

 

[omarsultan]

One of my concerns, though, is what happens if and when the car is eventually tested on a dyno by a respected source and found to make substantially less than 691 HP at the wheels. How is that going to sound to the general public? (There are dynos capable of accurately representing the horsepower of dual motor cars.)

Probably the one thing I would not be worried about--most gear heads expect the drop-off between crankshaft hp and wheel hp - as noted earlier, most articles I have read on the Hellcat are seeing ~620 on the dyno, with no concerns expressed.

 

[Andyw2100]

Probably the one thing I would not be worried about--most gear heads expect the drop-off between crankshaft hp and wheel hp - as noted earlier, most articles I have read on the Hellcat are seeing ~620 on the dyno, with no concerns expressed.

And if the P85D dynos at 495 or 505? (Or lower?) I'm pretty sure that's roughly the ballpark our gear heads are expecting.

 

[sorka]

I think some of us would be pretty much OK with Tesla's claims of 691 HP for the P85D if it turned out that dynoed at the wheels, and after accounting for losses, the car actually did make 691 HP initially. It is our contention that at no point does the car make the 691 HP, based on the fact that at no point does the battery put out more than 415 kW.

Actually, I think most of use would be ok with it making 691 hp at the battery (515kW) at this point. This is GROSS power before any standard is applied to restrict how power is made. Currently we're starting with (415KW) 557 hp at 100% SOC GROSS before any conversion losses...before the inverter and before it's turned into kenetic energy at the motor shafts. When a new standard is developed it's likely to have a large impact on what EV manufactures can claim. With ICE cars, J1349 uses atmospheric correction(not needed for electric motors) and prior to 2004 an assumption of 85% mechanical efficiency(moving to actual measurement of accessory loss after 2004 which is why many cars had a specified drop in hp claims without actually dropping in hp after 2004).

With EVs, expect to see new standards that level the playing field. For instance, ECE R85 in Europe doesn't allow more than 5% drop in voltage from the battery during the test so you can only pull as much current from the battery that doesn't exceed a 5% voltage drop. It also requires running the drivetrain at 80% maximum load for 3 minutes just prior to doing the hp measurement. Expect to see other restrictions like what SOC is used when measuring maximum horsepower. Is 100% fair when the car won't spend most of it's time anywhere near that? With gasoline engines you don't have to worry about losing power as your fuel level goes down. With the P85D, by the time you hit 50%, right in the middle of my normal driving range, you're already down 50hp.

 

[jpet]

I would not be satisfied if Tesla merely demonstrated that each of the motors could independently make 470 and 221 HP. The car, as an entire system, should be able to make the advertised horsepower.

Exactly, somewhere at some point, the P85D should be capable of producing the advertised 691 hp (= 700 pk in my country). I would be satisfied if we could see the car get 515 kW from the battery (logged via the API).

 

[rns-e]

Again, we are back stuck pondering exactly how Tesla got two 691hp. Personally, I do think 691 is a defensible number if they are hooked both motors up to the same pack at the same time.

As I have said before, if we assume the pack produces 400V at the pack terminals (a supposition some question) and the 1,300A that Elon mentioned, then we are in 520kW/691hp territory, but as discussed, there are a number of suppositions built into this.

I think it might be worthwhile pondering what would satisfy you on this front--you said something about showing the system delivering 691hp but I think that might be a bit of a squishy concept as the two drive units deliver power independently and are only mechanically coupled via the chassis. For example if they can show ~520kW flowing out of the pack, is that sufficient? I'd imagine a mechanical or drivetrain engineer and a lot of math could show how the two drive units interact to deliver hp to a virtual shaft.

My interest is piqued as to how this all plays out.

I would find it way harder to complaint if the there was 520kW flowing from the battery, yes.

It's un-surprising that you ignore the facts to fit your viewpoint. CR doesn't do the roll out, they specifically mention this. Several other automotive publications have gotten the advertised specs, and one has gotten better.

Interesting, were did you see that CR specifically says that, I have not been able to find it, although I have been looking.

- - - Updated - - -

So, just curious for the folks signing the letter....

It would appear to be industry practice to present total horsepower as the sum on the motors/engines in the drivetrain: the BMW says the i8 is 357hp (129hp + 228hp) and Ferrari says the LaFerrari is 963 cv (800cv + 163 cv). So, if Tesla provides documentation of the horsepower of the two motors on the original P85D (470hp on the rear and 221hp on the front), will they be satisfied that Tesla delivered the 691hp car per the published spec?

Have not checked what you are saying, but I know that the Golf GTE has a 102hp electrical motor and a 150hp ICE and the combined power is listed at 204hp

 

[smac]

On the other hand, I do think Tesla should have indicated somewhere on the P85D specs that they were now using 1 foot roll out, since they hadn't previously. Anyone shopping the P85D 0-60 time against other Tesla models' 0-60 times saw inflated differences due to the fact that 1 foot roll out was used to obtain the P85D time but wasn't used to obtain the other models' times.

And at the other end of the spectrum, they are doing a similar thing with the 70D, by UNDERSTATING it's range in the official EPA figures.

I get Tesla want to "up-sell" people to the more expensive models, I have no issue with this as a business strategy in general. However in the past the product differentiation was done with clever technical solutions, not by using different testing yardsticks across the range.

It has been a problem for a little while now, ALL the cars are so good, the marginal gains going up the range so small (more Superchargers less need for big batteries, S85D being P85 fast etc.)

When I first got my car, which was probably the first customer RHD S60, the Wh/mi was set at 300 on the energy display like all the 85s and US S60's.

Within a week I got a firmware update that jumped it to 345 Wh/mi. The effect of this is lower range readings on the dash, which I can only assume was done for "Showroom Appeal", with range being so much less of a factor in the UK market.

Does it make any difference to how far I can go, or the quality of the car, nope. Did it erode my trust in the brand, a little.

 

[sorka]

So, just curious for the folks signing the letter....

It would appear to be industry practice to present total horsepower as the sum on the motors/engines in the drivetrain: the BMW says the i8 is 357hp (129hp + 228hp) and Ferrari says the LaFerrari is 963 cv (800cv + 163 cv). So, if Tesla provides documentation of the horsepower of the two motors on the original P85D (470hp on the rear and 221hp on the front), will they be satisfied that Tesla delivered the 691hp car per the published spec?

That might be industry practice if the combined power is actually made. But what you really mean is industry practice when combining an ICE with an electric motor where both motors aren't drawing from the same power source and even then you have to ask if that's still appropriate give that the motors could produce their peak hp at different wheel RPMs. The electric side of the power train is likely to have a very flat power curve so it's probably not a stretch for them to just add up the two numbers provided that both are producing peak at *some* point together.

- - - Updated - - -

Have not checked what you are saying, but I know that the Golf GTE has a 102hp electrical motor and a 150hp ICE and the combined power is listed at 204hp

That's because they did the proper thing and only listed the maximum hp that both produce combined. My Prius is rated the same way. 70 hp ICE + 44 hp electric != 114 hp but instead == 110 hp because the peak of both don't exactly line up.

 

[Troy]

I think I understand why Tesla uses the term "hp motor power" and what it means. It means the theoretical maximum the motor could achieve by design. They use it because they are used to referring to these motors this way. Sometimes companies focus so much on internal communication, they lose sight of whether the information is relevant to the public. Currently Tesla has 3 different motors; 259, 382 and 503 hp. The motors are manufactured at second floor. If an engineer on first floor picks up the phone and says "we are running low on 85D front motors" it wouldn't make sense. The same motor is used in 70D, 85D and P85D. Instead he would say we need more 259's.

The S70 and S85 are interesting because they both have the same motor which has a theoretical maximum of 382 hp. That is the maximum power this motor can produce in a lab environment. It doesn't mean it will produce that much when installed to a specific car. For example it drops to 315 hp in an S70 but increases to 373 hp in S85. What would happen if that motor was designed to produce maximum 360 hp? Then the S85 would achieve 360 hp instead 373 because the design of the motor would be the holding back factor. To avoid this, by design the motors have slightly greater potential than can be achieved with the battery they are attached to.

What is interesting is that, somehow the horsepower P85D achieves is unknown, even though it is known for the other cars. If it scores same as 85D, the achieved number for the original P85D would be 556 hp. I don't know why Tesla didn't advertise 556. My guess is, they confused themselves too much with the theoretical numbers and Elon ended up mentioning 691 in a few interviews so they decided to stick with that.

	70	85	70D	85D	P85D original	P85D new
Theoretical max hp front			259	259	221	259
Theoretical max hp rear	382	382	259	259	470	503
Achieved hp	315	373	328	417	unspecified	unspecified
Achieved/Theoretical hp	82%	98%	63%	81%	unknown	unknown

 

[Wolfke]

Exactly, somewhere at some point, the P85D should be capable of producing the advertised 691 hp (= 700 pk in my country). I would be satisfied if we could see the car get 515 kW from the battery (logged via the API).

You mean 772 HP now? I can't imagine that they use different motors in the "new" P85Ds than in the "old" ones

 

[WarpedOne]

What is interesting is that, somehow the horsepower P85D achieves is unknown, even though it is known for the other cars. If it scores same as 85D, the achieved number for the original P85D would be 556 hp.

Nah, it is just marketing.

They could marketed P85D the same way as they marketed 85D - with max power output but then the people would go WTF? Both models have same max power, they must be the same cars, don't waste your money, it is a scam!!!!1111oneoneone
And all the work they did on improving maximum current to one motor and maximum torque at lower (and higher) end would go much wasted.

In the end the matters are stupidly simple. Each motor has its own limits, the battery has its own limits and the dynamic system of one battery, two controllers and two motors and one car as package has its own limits.
They beefed up front and rear motor/controller capabilities. The battery capability is above each of them by itself, but not above them combined. So they came out with 'clever marketing' of advertising (combined) motor power, that is pure sum motor/controller capabilities. Some incompetent dutch translators than went and translated that as 'max performance' or some such nonsense.

What could tesla do? Advertise P85D's 0-30 time and 70 - 100 time? With what would customers compare those numbers so they will see P85D as an awesome car? No other car company publishes those times.

What tesla could do and I would very much welcome such move is to publish what they already published for roadster - simple power/rpm chart.
But then again, 99% people would not have a clue what they are looking at. And would be totally confused by power starting at 0 at 0 rpm.

My point? There isn't one simple way of publishing the true technical specs and at the same time not shooting themselves into the foot by people totally misunderstanding those specs. People don't even understand there is no revving the engine at the start line in an EV.

 

[rns-e]

Nah, it is just marketing.

They could marketed P85D the same way as they marketed 85D - with max power output but then the people would go WTF? Both models have same max power, they must be the same cars, don't waste your money, it is a scam!!!!1111oneoneone
And all the work they did on improving maximum current to one motor and maximum torque at lower (and higher) end would go much wasted.

I just love that you can write this with a straight face. Because why should Tesla advertise the P85D truthfully when the reaction would be like you describe, just why? Makes no sense to do that, then it is better to find the most technical way to market to the end user :biggrin:

In the end the matters are stupidly simple. Each motor has its own limits, the battery has its own limits and the dynamic system of one battery, two controllers and two motors and one car as package has its own limits.
They beefed up front and rear motor/controller capabilities. The battery capability is above each of them by itself, but not above them combined. So they came out with 'clever marketing' of advertising (combined) motor power, that is pure sum motor/controller capabilities. Some incompetent dutch translators than went and translated that as 'max performance' or some such nonsense.

What could tesla do? Advertise P85D's 0-30 time and 70 - 100 time? With what would customers compare those numbers so they will see P85D as an awesome car? No other car company publishes those times.

What tesla could do and I would very much welcome such move is to publish what they already published for roadster - simple power/rpm chart.
But then again, 99% people would not have a clue what they are looking at. And would be totally confused by power starting at 0 at 0 rpm.

My point? There isn't one simple way of publishing the true technical specs and at the same time not shooting themselves into the foot by people totally misunderstanding those specs. People don't even understand there is no revving the engine at the start line in an EV.

Andy - you should address the letter to the incompetent dutch translator, not Elon. It is obviously not Tesla or Elons fault that only a few very intelligent users on this forum understands what they are saying and then on top of that having incompetent dutch translators translating into Danish. I found the address to make it easier for you.

Att.: Incompetent Dutch Translators Inc.
c/o Tesla Motors København
Bredgade 35
1260 København
Danmark

 

[WarpedOne]

Because why should Tesla advertise the P85D truthfully when the reaction would be like you describe, just why?

85D max power, 415kW
P85D max power 415kW
Yes, I have straight face when I understand what motor power means.

 

[wk057]

Lots of interesting comments caught up on here. I'm going to point out a few things.

Up thread it was suggested that Tesla came up with the individual motor numbers when testing the motors individually from the battery pack. If so, we know the pack can deliver ~550HP worth of power. If they tested them individually then why is the rear motor only 470HP when recently it's been re-rated for 503 HP? We know the car can output enough to test it at 503 HP. Same for the front motor. We know the car for sure can put out the newly spec'd 259 HP worth of power if it were running only that motor. I think this debunks that particular theory.

In any case, I think everyone would be completely fine if the car delivered 515kW from the battery to the motors at some point on the power curve. No one is expecting anything crazy like 691 HP at the wheels. 691 HP worth of power being fed into the system would be nice though. I'm not convinced even the P90D is capable of this though, based on the videos, which seem to still top out at just under 480kW. Much closer at least, though.

 

[rns-e]

85D max power, 415kW
P85D max power 415kW
Yes, I have straight face when I understand what motor power means.

If that are the true numbers, then I completely understand why Tesla introduced the term 'Motor power'. Just imagine if people were told that the only difference between the P85D and the 85D is only 1.1s (measured on different scales, of course, so in reality only 0.6s), then they might not pony out the extra $20k - cue the magic term 'Motor power' and line up all the fan boys telling everybody that did not understand that when ordering, that it is no way Tesla misleading anybody, because what would be the gain for Tesla in doing so?

This is the most far out defense of Tesla so far WarpedOne, but very entertaining

 

[yobigd20]

worth noting that Consumer Reports couldn't get 3.1sec either. their testing in insance mode showed 0-60 in 3.5 seconds. the original P85 was shown to do 0-60 in 3.9seconds so that really sucks there isn't much of an improvement here despite all the hype of '3.1'. Tesla Motors Inc (TSLA) P85D Just Killed Consumer Reports System

 

[MuppetOwl]

worth noting that Consumer Reports couldn't get 3.1sec either. their testing in insance mode showed 0-60 in 3.5 seconds. the original P85 was shown to do 0-60 in 3.9seconds so that really sucks there isn't much of an improvement here despite all the hype of '3.1'. Tesla Motors Inc (TSLA) P85D Just Killed Consumer Reports System

Motortrend did test the P85 to 3.9 sec using 1 foot rollout. Consumer reports dont use rollout. So the real 0-60 time for P85 is 4.2 to 4.3 sec. The P85D time using the BS foot rollout is 3.1 sec

 

[Alipapa]

Motortrend did test the P85 to 3.9 sec using 1 foot rollout. Consumer reports dont use rollout. So the real 0-60 time for P85 is 4.2 to 4.3 sec. The P85D time using the BS foot rollout is 3.1 sec

So Tesla didn't use the rollout time to advertise P85. Why they use the rollout time on P85D?

 

[peteyswift]

I'm more focused on the lack of communication on this issue from Tesla (yes, broken record). I think it is telling that they had detailed, technical, data-driven blog write-ups within one week from Elon and JB for incidents like the Broder article, fire safety, and range of the new Ds, but nothing on this hp/performance issue.

I will also echo a comment upstream: it should not be about the "whiners" vs the non "whiners"; the owners who want to bring Tesla down vs those that want to see them succeed. This is all about Tesla handling another issue and maturing as a company. No company grows without making mistakes and learning from them. It remains to be determined if the mistake was a technical one or a communication one, or both. Many of the signees, myself included, I'm sure are on their 2nd or 3rd Model S and have sold a bunch more to others. There is no way we would want to see this company not do well. I personally believe Tesla can save the world. But I also don't think any of us would lie to our children when they are doing something correctly, and try to steer them in the right direction. In this case, all I would like to see is a well-thought response like we've seen many times in the past. Any response will be met with great respect and appreciation.

 

[brantse]

Sorry for joining in late, and I apologize as I haven't read through the entire thread, but the thing that I think is missing is that HP is not a ubiquituous measure that applies equally to all cases. There's a reason that manufacturers of ICE's generally list a HP value at a specific RPM. Because that's the maximum power rating and it's only available at that speed. EV's have a much different power curve than ICE's and they can't be correlated directly. This is also the reason that the P85D will smoke anything with an ICE of the line, but often gets overtaken at higher speeds. I think that generalizations about comparisons of weight and HP ratings are going to lead to a lot of variance, especially between EV's and ICE's.