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Let's discuss Dual Motor range

Discussion in 'Model 3' started by ModelNforNerd, May 29, 2018.

  1. xav-

    xav- Active Member

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    Are those cheap overinflated Michelin tires going to be safe with all that Horsepower?
     
  2. Troy

    Troy Active Member

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    Here are the EPA scores once again in a simple table.

    [​IMG]
     
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  3. diamond.g

    diamond.g Active Member

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    Hmm, are they allowed to advertise an EPA rated range that is greater than the actual EPA rated range? Isn't that what Hyundai got in trouble for?
     
  4. ModelNforNerd

    ModelNforNerd Active Member

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    That's only for New England winter driving. I'll have something of my own choosing on there in the summer.
     
  5. Zoomit

    Zoomit Active Member

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    @Troy Doesn’t the 2018 EPA data (cells FG46 and FH46) infer a 330 mi EPA rated range for the Model 3 LR along with 345 city, 311.7 highway?
     
  6. Troy

    Troy Active Member

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    #366 Troy, Jul 18, 2018
    Last edited: Jul 18, 2018
    The actual EPA score is what they achieve during the dyno test but that's not the score EPA certifies. Instead, they offer two options:

    Option 1: Voluntary reductions to lower the score.
    Check out the screenshot here. It says voluntarily lowered in 5 places. The screenshot is from an EPA document you can download HERE. After you open the file, select the EV tab and scroll to the right.

    Option 2: Alternative multipliers to increase the score.
    In the table in my previous message, I converted the dyno scores to city range and highway range using the default 0.7 multiplier. However, car manufacturers don't have to use this. They can come up with their own multiplier. Tesla uses this option a lot for marketing purposes. For example, in this instance, they adjusted the multiplier just enough to achieve exactly 310 with the AWD version. They used 70.32% instead of 70.0%. The screenshot below is from THIS document. The orange columns are formula columns that I added. You can see the formula I have used. If you divide column E by F, you get the multipliers.

    No. Hyundai got into trouble because the advertised MPG numbers were too optimistic. In the past, GM was also sued because of MPG numbers. EPA doesn't want the car manufacturers to get into trouble. Therefore when voluntary reductions or alternative multipliers are used, the MPG numbers remain unaffected.

    The problems for Tesla with the accuracy of the EPA range started in 2012 when EPA made the test more difficult. Before that, the Roadster had achieved 245 mi EPA which was too optimistic. Using the same test, the Model S 85 should have scored over 300 miles. In fact, in 2012 before Tesla started production, they were already talking about 300 miles. (source). However, because EPA changed the test, the actual score was only 235 miles. Tesla played with the multipliers to increase the score to 265 miles. They used 79.6% when everybody else was using 70%. In the next two years, they improved the car and the score would have been 244 instead of 235 miles had they re-tested the car but they didn't. Outside of North America, the S85 displays 400 km (249 mi) which is pretty accurate.

    The biggest mistake people can make is to buy a used Model S 85 instead of the $35K Model 3 SR. These two cars have the same range. To be more precise, a used S85 with 4% degradation (which is typical) has the same highway range as the Model 3 SR with Aero covers on. You might say, we don't know the SR's test scores. That's correct but we know the cell counts for both Model 3 battery sizes. The LR pack has 4416 cells and the SR has 2976 cells (source). We also know that the LR pack has 78.27 kWh usable capacity (source: page 6 footer here). Therefore the SR is expected to have 78.27 * 2976/4416= 52.75 kWh usable capacity. We also know the weight numbers of both cars and we know the dyno scores of the LR. Therefore it's possible to calculate the SR's range. I recommend looking at the range table here.

    [​IMG]

    2018 Model 3 LR numbers are questionable. Something seems to be messed up. If you look at these two documents, on page 6 both of them show 06/16/2017 as the test date. In other words, there was only one test. The 2018 model was never re-tested. I recommend comparing the AWD scores to the 2017 LR scores instead of 2018.

    2017 Model 3 LR https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=39792&flag=1
    2018 Model 3 LR https://iaspub.epa.gov/otaqpub/display_file.jsp?docid=42148&flag=1
     
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  7. omgwtfbyobbq

    omgwtfbyobbq Active Member

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    I think the CSIs are just for emissions compliance. The SAE J1634 test results from the 2018 application are IMO what's needed to confirm what Tesla changed. My guess is that Tesla only reduced the reported range in the 2017 application, which hurt the 3's mpg ratings, and in the 2018 application reduced the reported range and energy used in proportion to the reduction in reported range so the mpg ratings would be accurate.
     
  8. jsmay311

    jsmay311 Member

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    I hate hate hate that we don't understand the discrepancy between the 2017 and 2018 numbers.

    I know it's not a huge difference, but I'm on the verge of changing my order from AWD to RWD based on the efficiency difference (efficiency is a high priority for me), and not fully understanding what's the deal with these ratings from a comparative standpoint (should we compare the 116MPGe to 126MPGe or 130MPGe) is driving me nuts.
     
  9. Troy

    Troy Active Member

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    @jsmay311, is the highway range more important to you or is the home charging cost more important?
     
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  10. clostridium

    clostridium Member

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    Try using the trial for TeslaFi and see what sorts of numbers you are getting. It provides a lot of insight into what is going on with your car and is worth the $5/month to use for the longer term. It also allows scheduling of many vehicle functions like charge limit changes, etc.

    Here's an example of what it will show after each drive:

    Untitled.jpeg

    This allows you to see actual electricity used, rated miles used, and efficiency and also info on many factors that influence those numbers like climate control usage and elevation changes.

    It also shows you info on your charging that is pretty handy.

    Good luck sorting this out
     
  11. jsmay311

    jsmay311 Member

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    Overall GHG emissions.
     
  12. ℬête Noire

    ℬête Noire Active Member

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    If the range fits your needs, SR RWD based is very likely going to be a little better yet (and lower manufacturing footprint by a bit, too). Of course that means the waiting game, and the waiting game sucks. ;)
     
  13. jsmay311

    jsmay311 Member

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    Yeah. I've considered it. But, as you correctly point out, it'd come with longer and more uncertain wait times and reduced tax credit (to go along with the shorter range and slightly slower acceleration).

    Reduced GHG is prob my primary criteria, but it's not the only consideration. It'd be a much easier call if I knew the SR efficiency ratings and knew with more confidence when delivery would happen. But such is Tesla life. :p
     
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  14. K-Gun

    K-Gun New Member

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    I'm in the same boat. Just placed an order for a dual motor M3, thinking it would get better range than the single motor model. I've got some time to make changes to the order, but range is of greater importance than performance or AWD.
     
  15. diamond.g

    diamond.g Active Member

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    I would switch if I were you. The RWD is more efficient than the AWD so it will be able to go farther on the same charge.
     
  16. EVnut

    EVnut DARΞLL

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    If only we had verifiable, hard data on that. And what the real-world inefficiency really was.

    After 20 pages of conjectures, I guess that's the one thing still missing.

    And for the record, I'm in the same boat as K-Gun. I assumed same range or better... and all the other benefits of AWD. The only negative being extra up-front cost. If the range *really* is going to be measurably lower, I'm back into the same quandary that I was when waiting for AWD to even be available to order. These first-world issues are gonna be the end of me.
     
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  17. ℬête Noire

    ℬête Noire Active Member

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    Once the motor configuration was announced it has just been a question of exactly how much shorter the real world range was going to be, and people coming to grips with that reality. ;)
     
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  18. Lasairfion

    Lasairfion Member

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    Having driven a number of All-Wheel Drive vehicles, and their non-AWD counterparts, I have never once had one outperform the standard two-wheel drive vehicle regarding miles per gallon or range of a full tank. I can only assume this would be the same for an EV.

    Thinking of it from a physics standpoint it makes sense since you've got more resistance and friction on moving parts and more power is required to actively turn more axles.

    I've always bought an AWD for the increased handling on corners, the better poor weather traction and in order to drive across a muddy field. If that's not in your purview then perhaps the rear-wheel drive option would be better.
     
  19. EVnut

    EVnut DARΞLL

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    Yes, that's the easy assumption... and true if this was a direct comparison. But it overlooks that internal combustion AWD vehicles have just one engine, and the torque from that one engine is then physically split to four wheels instead of two. The one motor is generally the same either way. And more friction is obviously introduced. With dual motor AWD in an EV, you now have two motors, and they can be quite different, and there is no physical connection between them. Thus they can also be geared differently before the final drive output. And the power ask from each unit can be precisely controlled for max efficiency or torque depending on need. It is quite possible to have one relatively inefficient motor augmented by a more efficient motor that then makes the whole system (on average) MORE efficient by driving all four wheels. Or in the case of what Volvo has done, driving one set of wheels with internal combustion and the other set with battery... the system becomes more efficient with AWD than it was with just one set of wheels being driven with ICE.

    It isn't as simple as it seems on the surface. Many variables to consider.

    We know for sure that the AWD car will be heavier, and that alone will reduce efficiency when all else is held equal. Next is that there will be more friction with a motor always attached to a second set of wheels. "Freewheeling" is not a perfectly non-frictional process.

    And now I'm going to expose my ignorance... my ignorance in something that I've even tried to research for years! What really happened with the Model S when the D was introduced? Is it possible to do an apples-to-apples comparison with a RWD and AWD Model S? Didn't it become slightly more efficient on average when the front motor was added? Did I just dream that? Was it fake news? Or did this really happen? We can't compare today because there's no RWD offered in S or X. Did everybody demand less efficiency? Was the D version so much better than everybody was happy with reduced efficiency?
     
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  20. EVnut

    EVnut DARΞLL

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    Exactly.

    If it is unmeasurable in the real world, I can live with the reality. If that "exactly how much" is 25 miles of range, I'm gonna have a problem with it. Can't come to grips with the reality until we know the reality. And I do love me some good reality.
     

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