MarcG
Active Member
Not yet, but I will very soon as I'm taking my big trip up to Oregon at the end of the week.
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Not yet, but I will very soon as I'm taking my big trip up to Oregon at the end of the week.
I've seen this a few times but it is always without citation. I wonder if this is true or just conjecture, but I didn't spend much time looking.
JRP3
Hyperactive Member
The mileage rating drops between the 19" and 21" but to be sure, is that due to weight? The contact surface is very close to the same, so its the only thing that I could link to the measurable decrease. And, if that is the case, the cast stock wheels are quite heavy - could one offset mileage positively in the same respect by opting for a 1 piece aluminum wheel - you could probably expect a haircut in wheel/tire weight as much as 25% to 30%.
I have a set of 21" ADV wheels coming in about a week and I have the 19" wheel set (which I believe will also be heavier). Happy to do a largely unscientific experiment. If someone has the physics figured out already, that might save me some time :smile:
I've seen in the P85D delivery tracking thread a couple of initial reports of lower highway range than expected... this thread seemed the more appropriate place to discuss this.
I'm wondering if anyone uncovered what the status of "normal" mode is?
Unless I missed something, it's not been seen in the cars despite the original D announcement indicating the car would have "normal", "sport" and "insane." As I understand EPA rules, if Tesla had a "normal" mode, that could be the mode that Tesla used to calculate the D's EPA ranges (and Tesla's own 65 mph numbers). That could be a decent chunk of the explanation why current cars driven in "sport" mode (let alone "insane") are not looking as efficient as rear wheel drive cars despite the better highway efficiency on the Monroney sticker. Of course, that leaves the question, has normal mode been scrapped or for some reason not been activated just yet (and would Tesla be able to send the car out with the stickers based on a mode, normal, not yet active on the car)?
I'm wondering if anyone uncovered what the status of "normal" mode is?
Unless I missed something, it's not been seen in the cars despite the original D announcement indicating the car would have "normal", "sport" and "insane." As I understand EPA rules, if Tesla had a "normal" mode, that could be the mode that Tesla used to calculate the D's EPA ranges (and Tesla's own 65 mph numbers). That could be a decent chunk of the explanation why current cars driven in "sport" mode (let alone "insane") are not looking as efficient as rear wheel drive cars despite the better highway efficiency on the Monroney sticker. Of course, that leaves the question, has normal mode been scrapped or for some reason not been activated just yet (and would Tesla be able to send the car out with the stickers based on a mode, normal, not yet active on the car)?
1. The 21" tires have a stickier tread compound than the 19" tires (when comparing OE tires).
2. The 21" wheels have more mass at the outside of rotation. There are two components: A) The rim is further out and B) The tread is wider so there is more weight in the tread area (mostly the belts). The wheel and tire assembly has a straight line component, an unsprung weight component, and a rotational component, so energy is used to accelerate the assembly in the direction of travel, move it up and down, and rotate it around the hub. For this part, rotating it around the hub is the major part of the difference between 19" and 21" followed by up and down movement.
dhanson865
Well-Known Member
so the range didn't get worse all the sudden, just the EPA added a fudge factor and Tesla didn't make a clear comparison chart.
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As I mentioned above these claims about the EPA changing the criteria don't seem to have any citation (unless I keep missing it). It would be nice if someone could point to where this is actually documented.
Andyw2100
Well-Known Member
And breser has pointed out a number of times, in a number of threads, that based on his fairly extensive research, that 10% claim has no merit. I'll try to find his most recent post on that, and come back and link to it.
Edit: breser's post: #3309 here: Tracking P85D delivery thread - Page 331
I don't have access to the SAE standard, so I can't prove it outright, but my assumption is that the change to the requirements (which is well documented in the case of the Nissan Leaf, and "resolved" by removing the 80% charging option there,) is part of the update to SAE J1634, which was revised in October of 2012 and is repeatedly referenced in the EPA documentation (test per, report results per, etc.)
Here's the SAE page:
J1634: Electric Vehicle Energy Consumption and Range Test Procedure - SAE International
I'm not curious enough to pay $70 for the spec - I don't know if someone might have access to it from work or something.
There's a clear date and proof that there was an opportunity for new requirements - which matches with Nissan's reporting of new requirements. It doesn't prove there are new requirements that apply to the Model S, but I don't know of a way to do so short of buying the spec.
Edit: Oh, and the rationale for releasing a revision says:
Walter
Andyw2100
Well-Known Member
I think you may be hitting the nail on the head here.
There has not been any mention of what happened to "normal" mode. That might be the difference.
stopcrazypp
Well-Known Member
While the claim it was just a straight 10% decrease has no merit (the actual procedure is averaging of two driving modes), the claim that the lower range number is solely because of lower efficiency doesn't have merit either.
This is because if you do even a cursory examination of the MPGe numbers versus the range numbers, the math doesn't work out. First thing is that the combined MPGe is exactly the same at 89MPGe, so unless Tesla limited the usage of the battery, the range should remain the same for the same 85kWh battery.
The next assumption is that it's because of the lower city MPGe (86 MPGe vs 88 MPGe), but that's still only a 2.3% difference. 242 vs 265 miles of range is a 8.7% difference. So even if the test was 100% city (which it isn't), the numbers still don't work out. There's something else in there other than the slightly different efficiency in the city.
An article recently called attention to this note at the bottom of the model S builder. Not sure if this has been referenced already and this might be off topic; however, there is some indication that performance may improve in the future. This may just be acceleration but I guess this could be range related too.
** The P85D top speed is currently electronically-limited to 130 mph. In the coming months, we will be able to upgrade the car free of charge to enable a 155 mph top speed. This free update will be available for the lifetime of the car (not limited to the first owner). Additionally, an over-the-air firmware upgrade to the power electronics will improve P85D performance at high speed above what anyone outside Tesla has experienced to date. In other words, the car will be better than you experienced. This free upgrade will be rolled out in the next few months, once full validation is complete.
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** The P85D top speed is currently electronically-limited to 130 mph. In the coming months, we will be able to upgrade the car free of charge to enable a 155 mph top speed. This free update will be available for the lifetime of the car (not limited to the first owner). Additionally, an over-the-air firmware upgrade to the power electronics will improve P85D performance at high speed above what anyone outside Tesla has experienced to date. In other words, the car will be better than you experienced. This free upgrade will be rolled out in the next few months, once full validation is complete.
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I agree with this - there is something missing; however, what is becoming clear from the various owners reporting their consumption is that the Wh/mi has gone up with the current version of the P85D. Various drivers are comparing drives with similar if not identical conditions and coming back with a higher number for the P85D. Given this measurement is based on actual driven miles and actual electrical consumption, I think it is almost a certainty that the P85D does not have the range of its predecessor. Perhaps this will be tuned with future updates but for now, unless we get some contradictory data points from new owners I think we have to accept that it is worse.
I agree that it remains possible, even likely, that the EPA number being based on something other than a 100% charge is part (or possibly all) of what's going on with the range numbers. I say likely based on the point stopcrazypp referred to, that is, same exact combined MPGe for P85D as the RWD 85 was rated in 2012, but lower EPA range.
To be clear, I see no reason to think that the Leaf having an 80% charge mode and 100% mode averaged to 90% means that the "D" vehicles are being rated at 90% charge, but I do find it realistic to think the policies that forced Nissan to use something other than a 100% charge led to Tesla's use of a number other than a 100% charge. As Tesla's cars offer the slider to set range (and, if I'm not mistaken, have made past statements about selective use of 100% charges) it seems plausible that this led to some kind of negotiation with the EPA as to what percent of charge to do the testing. For all we know this negotiation isn't over (well, perhaps not over in the eyes of one of the two parties).
I think there's probably multiple pieces to behind the confusion. Just for fun, remember this... Elon stated (pretty sure early August this year on Q2 earnings call) that the S produced currently was hundreds of pounds (think he said a few) than the first ones made in 2012. If Tesla is keeping it's original 265 range rating based on the 2012 testing, some owners actually have newer 85s and P85s that would have gotten better EPA range ratings had they been tested again with the 2012 method. So somebody today comparing their new P85D vs their old P85 has yet another variable to consider... how old was that P85.
I think more likely than not, Tesla will eventually put all the cards on the table on this one... I'd surely like that!
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breser
AutoPilot Nostradamus
I don't have answers to these issues. Wish I did. I've actually started trying to ask Tesla for the answers to this. So far I've been getting a lot of silence or just repeating what's on the website already. I've asked again pointing out how the numbers don't really add up very well with the hope I'll get more concrete answers.
The correct number to use to compare the old versus the new MPGe is 250 not 242. The old tests are on 19" wheels, the 242 is based on 21" wheels, the 250 number is also based on 19" wheels. So that brings the range difference due to the vehicle (and not the wheel change) to only 5.7%. Granted that's still more than 2.3%, but not nearly as dramatic of a difference.
If you mean the article I referred to it was unremarkable but I picked up somewhere in the follow-up comments that the Tesla Model S builder had the note that I quoted in my post. I copied it from the bottom of the Tesla page verbatim. It is strangely worded.
breser
AutoPilot Nostradamus
There was a comment on the greencarreports article pointing out that text is at the bottom of the design page now:
Model S Design Studio | Tesla Motors
Just scroll all the way to the bottom.
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I have access to it now and no there was no change to the spec other than making it so the tests could be completed faster by doing multiple drive cycles in the same test run (each run discharging the battery fully) rather than running a single drive cycle per test run.
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