Model 3

AWD less efficient thatn RWD

Interesting analysis from Elektrek that "a CARB filing for the Tesla Model 3 Dual Motor and Performance versions showed that they performed 8% lower in the “urban dynamometer driving schedule” test than the rear-wheel-drive version."


The opposite is true with the Model S, the AWD is more efficient than RWD and thus has greater range. I ordered the AWD which has better acceleration and presumed efficiency, but now question that decision with the probability that actual range will be greater in the RWD.
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Comments

  • edited July 2018
    My question is: Does the “urban dynamometer driving schedule” accurately reflect real-world driving. When you say the AWD Model S has better range, did it also perform better on this test?

    I also ordered the AWD for the performance and while an 8% hit isn't the end of the world, it does make me concerned - especially if I could change to RWD and possible get a car sooner.
  • edited July 2018
    Speculation: It’s possible that RWD is SW neutered to 310, so range across LR variants will be the same, but you will have more headroom on a “full” battery, so less degradation with RWD.
  • edited July 2018
    Remember that this performance test is with 20” wheels. It 18”
  • edited July 2018
    The tires make a +/- 10% difference. Better tire driving performance means less range.
  • edited July 2018
    Also realize that Performance Model S has slightly less range than non-performance, so until we see tests on non-performance AWD it’s unclear whether it is the AWD or the extra power transferred to the motors that is causing this.

    @tesla I’ve been thinking the same thing for a while.
  • edited July 2018
    Isn’t both motors on the 3 the same size. So it’s not like the S where the front motor is smaller where it can be used on the highway for better efficiency. With two same size motor you can’t be more efficient than having one motor.
  • edited July 2018
    I read somewhere else that the RWD was EPA rated HIGHER than 310 and Tesla requested that the EPA lower the range to 310. I suppose Tesla requested this to minimize eating further into S sells and also so the RWD/AWD were similarly rated. I think the "true" RWD range was closer to 330 (from what I read).
  • ed2ed2
    edited July 2018
    I also ordered the AWD non-performance M3, thinking that there was no downside, other than the extra money. I am wondering if it was a good decision. I was hoping that the efficiency for the AWD would be at least the same if not better than the RWD version, just as is claimed on the model S. I know that the performance version will get lower mileage because of the larger wheels, but I guess I will just have to wait and see about the non-performance version.
  • edited July 2018
    Tesla anticipated this and asked for 310 mile certification though RWD gave some 340 miles in EPA testing. So they will adjust the software and give you 310 miles in AWD too.
  • edited July 2018
    Model S use three-phase, four-pole AC and copper rotor, 2 motors will improve the efficiency. model 3 use permanent magnet motor, it more efficient than Model S's. no more improve when adding one motor
  • edited July 2018
    I could have sworn the design page mentioning the AWD being more efficient. Of course, I can't access the design page for some reason as I just get a blurb about the M3 attaining the "highest safety ratings". They definitely should stop advertising the M3 as starting at $35k (before incentives) which it absolutely does not.
  • edited July 2018
    @wqlhh Read this article to read about the M3 AWD and that the rear motor only is permanent magnet and the front is AC induction.

    https://electrek.co/2018/05/19/tesla-model-3-dual-motor-performance-version-ac-induction-permanent-magnet-motor/
  • edited July 2018
    Actually, theoretically range of AWD may be better, not worse, because of regenerative braking of front motor. With RWD to save on energy you will use rear motor for regenerative braking and use front brakes if you break harder and it means energy loses. With AWD you may use both motors for regenerative breaking and save more energy. Also,
    I believe that front and rear motor will be different, not the same and it will allow better economy, as one motor optimized for more torque on slower speed and another one for less torque. Software control distribution of power between the motors to optimize. So, despite Tesla claim the same range for AWD and RWD, I think that AWD has more room for making range better.
  • edited July 2018
    “SW neutered”? As in they are increasing the reserved capacity or under stating the remaining range on the screen?

    It would be great to know if it’s the former as it means we can get closer down to zero or charge to a higher percentage and still be within the batteries’ “happy zone”.
  • edited July 2018
    I guess we will not truly know until we get more specs on the motors but... we do know they will be different types per Elon. Every part of a car makes a difference in the mpg including height of the car (coefficient of drag), type of tires (rolling resistance), size of the wheels (rotating mass) and the torque curve at a certain throttle input. I am willing to bet that the lower height, larger wheels, stickier tires, different torque curve and different regen are all contributing factors in this rating.

    But this is only a theory... a car mpge theory.
  • edited July 2018
    steven.h.goldberg: Ah. So, 'less efficient' in one portion of a five-cycle test. Pardon me while I ~*yawn*~ Oh, and how much 'less efficient' is a BMW M3, AUDI S4, or Mercedes-AMG C63..?
  • JADJAD
    edited July 2018
    Does it really matter? It is a 0-60 in 3.5 seconds AWD EV that supposedly beats a BMW M3 on the track and goes over 300 miles on a charge. Wow.

    Drive 5 mph slower in the P and your range will be better than a RWD. All of this is noise level as far as range goes. Speed is the biggest factor by far. Look at todays Electek article where the 3 went over 1000 km (600+ miles) on a charge. Amazing range if you are willing to drive like that.
  • edited July 2018
    The test in question is not a test that gives a range result. There could be several factors that could invalidate the assumption that the AWD has less range than the RWD based on this test. One of them is the 2nd motor regeneration capacity, as mentioned above. And there are most certainly others.

    I don't see these results as any validation of overall efficiency or range. There are reasons that other types of tests are relied on in the industry to determine published range numbers.
  • edited July 2018
    Why are we discussing the results of a test with questionable testing methodology? In the almost 5 years I have on these forums, I have never seen anyone bring up "CARB" testing results for either the S or X. I know what CARB is, but I wasn't aware that they published their own EV range numbers.
  • edited July 2018
    @Jordanrichard Its because we live for every little bit of info we can get and this is the most recent info we have on the AWD versions and there are previous results from both the S and the RWD versions. Could mean something. Could mean nothing. Just something to talk about. :)
  • edited July 2018
    @jordan
    CARB isn't the issue anymore. The Maroney sticker shows it's less range via the mpge
  • edited July 2018
    So somebody has taken delivery of an AWD M3 already and posted a picture of the Maroney lable?
  • edited July 2018
    @jordanrichard. Not exactly. A Tesla employee leaked the Monroney label and followed up with additional pics. https://old.reddit.com/r/teslamotors/comments/8yxmp0/weve_received_our_first_performance_model_3/
  • edited July 2018
    Yes the performance version also has 20” wheels and would have been tested that way by the EPA. This could explain the difference on the sticker.
  • edited July 2018
    The front motor is an induction design optimized for power. It is less efficient than the rear motor which is based on switched reluctance design. If the front motor runs it will average down the efficiency. If not it also reduces efficiency because it adds weight and drags the front wheels.
    Possibly driving all four wheels can be more efficient, but I'm not sure the gain from that is sufficient to overcome the above limitations.
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