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Model 3 dual motor AWD optional

Discussion in 'Model 3' started by pr0teu5, May 16, 2015.

  1. pr0teu5

    pr0teu5 Member

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    #1 pr0teu5, May 16, 2015
    Last edited: May 16, 2015
    Hello everyone. One thing that I noticed is that everyone seems to come to the intuitive understanding that the base 35k version of the Model 3 will be a single motor version, but after thinking about it for a little bit I'm not quite so sure.

    At first blush it would seem like an AWD model would be significantly more expensive, but when you look at it more closely this may not be the case. Unfortunately I didn't really have to time to do something rigorous, but I think this might be a sketch for an argument for a base AWD version of the model 3.

    So first we must realize that the motors, gears, and power electronics will be more expensive for an AWD set up. In general the price of an electric motor scales as the square root of the motors horsepower. So assuming that Tesla is shooting for 250hp we can find he difference in price for the motors.

    Assuming two 125hp motors vs. one 250 hp motorPrice ratio = 2*sqrt(125)/sqrt(250)=1.41

    So assuming that the 250hp motor cost approx $2k, I have no idea if this is in the right ballpark, the two 125k motors would cost $2828. So we have $828 we need to make up.

    However, it is the case that due to always being able to operate the motors at this maximum efficiency point, the AWD configuration is more efficient than the SWD configuration. At first blush this doesn't seem to make much difference as the p85 has a 265 mile range and the p85D has a 270 mile range, not a significant difference. However we have to remember that the p85D is significantly heavier than the p85 lowering the range.

    We can therefore perform a calculation to see what the change in efficiency would be in the case that they had the same weight.

    Assuming a 4200lb weight for the p85 and a 4400lb weight for the p85D, and that range depends linearly on weight which it generally doesn't.

    265 miles *(4200lbs/4400lbs) = 252 miles(270-252) =17/265 ~7% efficiency increase.

    Now you ask why even consider the two cars at the same weight as in the real world a dual motor setup will obviously weight more. However, what we must consider is that when tesla is designing the car and the battery pack from scratch they get to choose the capacity they need. So with a higher efficiency they can select a smaller pack.

    If we assume that a 50kWh pack is required for their 200 mile target with a 7% increase they would only need 46.5 kWh. If we assume even a very low price for batteries $200/kWh this offsets $700 of the cost of the AWD. Leaving only $128 of the cost left. If we assume a higher cosf batteries as in the 7kWh powerwall it could amount to nearly $1500.

    As for offsetting the weight if the powerwall weights 220lbs then 1/2 of that weight is 110lbs so that goes quite a way to the offset.

    Summary

    The higher efficiency of the AWD configuration could make it less expensive or negligibly more expensive to sell a something like a 46.5kWh Model 3D rather than a 50kWh Model 3.
     
  2. Red Sage

    Red Sage The Cybernetic Samurai

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    I believe there is a strong possibility that the base version -- no, ALL versions of Tesla Model ≡ will be dual motor all wheel drive configuration. Every direct competitor in the range of $35,000 or more offers AWD at that price point. Even though many buyers don't actually need it, AWD is considered as much of a safety feature as ABS thanks to marketing efforts by others in the industry. Thus, the perception is that it should be a standard, included feature -- like seatbelts, rearview mirrors, and grab handles.

    Tesla Motors and Elon Musk have long stated that their Generation III vehicles will be built to compete directly with the leader in this market, the BMW 3-Series. Whether deserved it not, those cars are the perennial sales leaders in class. They are also the best selling vehicles in the BMW lineup. And they have a reputation that places them at the pinnacle of automotive excellence as the standard bearer for what it means to be at the wheel of what they term 'The Ultimate Driving Machine'.

    So, with that very hard task before them, to overcome decades of deeply entrenched ideals about what it means to drive a car, Tesla Motors must make absolute sure the Model ≡ is up to the task. For some this means it absolutely must not be a front wheel drive car, because there is no FWD 3-Series. That would lead some to suppose that also means there must be a rear wheel drive version, in order to satisfy the expectations of legions of fans of induced oversteer while testing their skills with RWD. But that is a purely emotional argument, and may not stand up to cold, hard, analytical inspection.

    See, the problem is that, as Elon has indicated, Tesla cannot get away with building cars that are simply 'just as good' as other cars -- even exceptional ones. They must build cars that are better, than all the other cars, or no one will have a reason to buy them. And the evidence is clear that dual motor AWD is simply better.

    The handful of lost sales from those who despise AWD will be dwarfed by the torrent of orders from those who demand it. The same as those who want to hear a loud, roaring engine, or must have a clutch and shifter so they can 'feel alive' while they 'tame the beast'. Tesla Motors has a lot of good reasons to go with AWD and dual motors standard across their entire product line. Now they simply need the courage to implement that strategy over any and all objections.
     
  3. gregincal

    gregincal Active Member

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    AWD in an electric car is different enough from an ICE version that I can't imagine somebody deciding to buy an electric car will reject AWD for emotional reasons. If they decide to have a non-AWD version it will just be for cost reasons. They have shown that an AWD version is superior.
     
  4. Nomad

    Nomad Member

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    I'm also of the opinion that there will not be a single motor variant for the Model 3. Like Red Sage suggested, Elon wants to convince the world that electric vehicles are far better than their ICE counterparts, not simply on par. The idea that we'll get a sub 200 hp motor configuration in even the base Model 3 is ludicrous to me.

    That said, I think the most important factor that Tesla will consider is power train assembly and manufacturing efficiency. I wouldn't be surprised if all versions of the Model 3 have two 221 hp motors. This is the same two motors found in the 85D, the front motor of the P85D, and likely the same two motors in the 70D (albeit with less voltage and perhaps smaller inverter). Imagine the incredibly efficient manufacturing process and economies of scale from using the same motor in all of their lineup. It would allow for Elon's end goal—a mass market car that outperforms its ICE competition. Optioned out, Model 3 will be in a totally different class.

    The real problem they'll have to deal with is differentiating the Model 3 from the Model S and X. I suspect that will be accomplished by much larger batteries in the S&X, probably to the tune of 85 kWh and 120 kWh around the time the Model 3 comes out. Those figures are based on a 40% improvement over 5 years, which is 20% less than the oft-stated figure of 100% over 10 years. Specifically, the original 60 x 1.4 = 85 kWh and the original 85 x 1.4 = 120 kWh.

    As an aside, Elon's passion to demonstrate how awesome electric vehicles can be is the big reason I'm a fan of Tesla. If someone else was CEO, they would rather focus on a 5% increase in margins or whatever and settle with 180 hp Model 3. Elon wants to change the world's perception of what an electric car is. That's how you convince people to move to sustainable transportation. Hopefully I'm not way off the mark here. :redface:
     
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  5. TEG

    TEG TMC Moderator

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    I hope they make them all as AWD. That would be great.
     
  6. mrdoubleb

    mrdoubleb Active Member

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    #6 mrdoubleb, May 17, 2015
    Last edited: May 17, 2015
    You know, you do bring up a good point. I too have to force myself to get rid of my ICE thinking where a 90hp engine is a lot cheaper to produce than a 400hp. Nevertheless, 2 motors is twice the cost, period.

    Anyone knows how those costs (of high performance) scale for electric motors and inverters? Also, do we have a guess of the manufacturing costs of these Tesla motors?

    Having said that, inverters aside, once you go several hundre hp, my understanding is there is a lot of things that become a lot more expensive with it, no matter what drivetrain you use. I am thinking wheel and tire sizes (go ballistic with costs above the mainstream sizes), suspension, brakes, etc. Not to mention burning through 2k worth of tires every 5k miles feels a lot difderent for the 100k car buyer than the person who stretched from a Golf to a 3.

    So there may be a sweetspot for Model 3 where they can still go with the 195/15 or 205/16 of the compact class for the base model.
     
  7. wallet.dat

    wallet.dat Member

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    Exactly. The T≡sla Model ≡, if it is to compete with the BMW 3-series, will have to feature 400hp at the very least.
     
  8. Red Sage

    Red Sage The Cybernetic Samurai

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    There is no way in [HECK] the Tesla Model ≡ will be classified as a 'Compact' car. The EPA does their size classifications based upon usable interior volume and cargo space. Please note the AUDI A8 is Midsize, though it is longer than the Tesla Model S, which is a Large car instead. The Model ≡ will be Midsize at the very least. The Toyota Mirai will be lucky to get a Compact rating, because a fuel cell, battery pack, and hydrogen fuel tank all take up space.

    Take a look at the BMW 335i. That will be the performance target for the base version of Model ≡. It will only get better from there.
     
  9. mrdoubleb

    mrdoubleb Active Member

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    There are several standards for categorizing cars by size, I took the "compact" label form the BMW 3 series wikipedia page where they classify it as compact exectutive car. The EU calls that D segment, the US says mid-size.

    In any case I was just pointing out that more HP means bigger wheels and tires and brakes so higher costs (and maintenance costs). The BMW 3 starts at 116hp in Europe with a 205/16 tire and goes up to 306hp on 225/17. (Of course the M3 is a different story at 431hp and mnster 255-275/18 wheels).

    All I am sayng is that it would make sense to have a base model with less insane specs to achieve the 35k and appeal to folks who are also worried about running costs (like tire replacement, buying a second set of wheels for winter tires, etc.)

    That may mean a RWD entry model with no more than 200hp. Doesn't mean they can't produce a monster that would eat the M3 for breakfast and cost the same (60k).
     
  10. wallet.dat

    wallet.dat Member

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    IMHO T≡sla has always had the upper-end in it's cross hairs. Let the other auto makers produce electric cars that can compete with base model ICE cars. I don't think that's what T≡sla is looking to do for the ≡. If they're going to compete with the BMW 3-series, I'm betting that T≡sla has its sights set on the upper range in that line.
     
  11. mwulff

    mwulff Member

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    Europe really is a different place than the US when it comes to cars. Here AWD is rare and not really seen as essential. AWD is considered something that people who live in mountains need and the rest of us are better off without it.

    That said there is very little penalty for Tesla if they go AWD only.

    If they target the 3-series they will need to take on the 316 and the 318 (the most popular models) with about 110 hp+. So not really in M territory at all.

    Of course since HP is easy and cheap with an EV they might as well go for 250 hp which puts them in line with the absolute top 335i. The real problem with that is that the cars are all but impossible to insure in Europe.

    Cars with much more than 120 hp are considered muscle cars and pay extreme premiums on insurance. Especially if the driver is young.
     
  12. mrdoubleb

    mrdoubleb Active Member

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    #12 mrdoubleb, May 17, 2015
    Last edited: May 17, 2015
    Yeah, and not just insurance. In my country there is a list of purchase and annual car taxes related to the performance of the car. Of course there is always talk about what execptions EVs should get...

    In any case, the question of AWD only is really a question of how much extra cost is it to have e.g. 2x100hp instead if 1x200. I am sure that designing the 3 means accepting a few compromisies (materials used, etc) so everything has a cost: e.g. ok, we take the higher cost of 2 motors, but what do we give up to stay within budget?
     
  13. gregincal

    gregincal Active Member

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    I just want to point out in assessing competition that the Model 3 will be $35K in the US. Given the current exchange rate and Tesla pricing structure I wouldn't be surprised to see it starting at around 38-40K Euro (US price plus $3k shipping plus 20% VAT). That's not 316 prices, more like 328 prices. Of course who know what exchange rates will do between now and then to make the Model 3 more or less competitive in Europe.
     
  14. SmartElectric

    SmartElectric Active Member

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    What is conveniently ignored here is the cost of the non-motor elements of dual motor AWD, namely, multiple inverters ($), front wheel drive components such as half shafts and associated bearings ($) which would not otherwise be required if RWD was chosen.

    Tesla has chosen to outline ONE thing about the Model 3, price. They haven't provided any other guidance.

    Price will be the deciding factor of what comes standard and what doesn't.

    Personally, AWD is a requirement here in Canada, so no matter what, I'll be looking for that, even if I need to pay extra above the quoted base price.
     
  15. dlinkeg

    dlinkeg Member

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    I agree that the Model 3 will likely appear with AWD, since Elon Musk desires to surpass any and all $35K "comparable vehicles". To leave out AWD, especially since the 70 series is only AWD, would be a big surprise. No matter what appears in the final version of the Model 3, I can't wait to replace my orphan Coda with an EV that has a company behind it who will innovate, support, and survive.

    I want to be on the waiting list YESTERDAY. I never could wait very well.
     
  16. Cebe

    Cebe Member

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    They may need to make the "default" AWD so that they hit the 200mi target range?
     
  17. Model 3

    Model 3 Active Member

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    And that just proves that Norway is not a part of Europe ;) ... on the other hand, we do live in the mountains (a lot of us at least). :p
     
  18. mwulff

    mwulff Member

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    Yup. Norway is classified as mountain. ;) but you have a lot of rwd model s's
     
  19. pr0teu5

    pr0teu5 Member

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    This is a good point and was something that I was thinking about when doing my analysis. However, I had no real way to estimate this cost as I didn't have any real idea how these components scaled. We could make the assumption that these things scale approximately that same way that the motor(s), as the square root of the horsepower required, but then we would need to know how much the entire drive system costs, which I don't really have a good estimate for.

    This is why I said that the argument presented wasn't so much a rigorous argument, but the outline for one. I was mainly just me thinking out loud.

    I think the larger point though, is that by adopting an AWD layout in a model where the size of the pack can be chosen from the beginning the efficiency increases from the AWD have the possibility of offsetting, at least in portion, the increased cost of the AWD system.
     
  20. David99

    David99 Active Member

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    Dual motor in an EV is not automatically more efficient. The only reason the Model S with dual motor is more efficient is because they are using the old, power optimized, large rear motor and then a newer, smaller and more efficient front motor. By switching off the rear motor they can make the Model S go a little more efficient. But that also means if it had only the newer, more efficient front motor it would be even more efficient, lighter and cheaper to make. So dual motor is not better from an efficiency and cost point of view. It is worse. The Model 3 is primarily about cutting the cost down. It is also a space issue. The dual motor Model S lost most of its frunk space to the extra motor. I use the frunk a lot so I'm glad I have a rear motor only.

    I'm pretty sure the Model 3 will come with optional dual motor, but also a front motor only configuration. Most cars sold in the 35k range have front or rear wheel drive only. Most people that buy these cars don't even know which wheels are driven by the motor. They really don't care because it makes no difference to their daily driving. They care about cost and range. Model S owners are a very different group. They don't care about cost, they care about performance and technology. Model 3 buyers will be a different group.
     

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