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100D vs. P100D and towing

Discussion in 'Model X: Driving Dynamics' started by j-rho, May 6, 2018.

  1. j-rho

    j-rho Member

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    This seemed like a good place to ask, vs. starting a new thread.
    Am sold on a MX 100, and plan to tow with it from time to time. Thanks to everyone who’s taken the time to chronicle their adventures!
    Instead of an airstream, will be pulling a race car in a small light aluminum trailer (96” wide but only 62” interior height, ~4900lb. fully loaded). I’m in San Diego so there are hills in most directions.
    The remaining purchase indecision is related to regular 100 vs P100. The P has slightly shorter range in regular use, but I wonder if the different parts would net greater efficiency (thus slightly longer range) when burdened with a trailer?
    We see this regularly in the ICE towing world, when bigger engines are less efficient unladen, but become more efficient than smaller engines when both are tasked with heavy loads.
    I don’t have the EE background needed to analyze the hypothesis, but thought I’d raise it to the clever group here.
    If the P were likely to be able to cover even just a few extra miles with a trailer, might be the last bit of rationalization needed to go with the (otherwise irrational) P. :)
     
  2. ohmman

    ohmman Maximum Plaid Member

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    The P will be limited to towing 3500 lbs unless you change the wheels (it comes with 22s if I'm not mistaken). I feel pretty confident that your range will not be improved with a P variant over a standard 100D.
     
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  3. ecarfan

    ecarfan Well-Known Member

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    I don’t think that would be the case for a Tesla. The more powerful rear motor in the P100D is slightly less efficient, hence the slightly lower maximum range. I do not see why it would be more efficient when towing then when not towing. The significantly decreased range when towing is primarily due to the added drag of the trailer, not the weight of the trailer.

    I recommend you go with the 100D. Take a test drive. I am confident that it offers more rapid acceleration than any street car you have ever driven.

    All that said, “~4900 lb” is right at the maximum an X is rated to tow with 20” wheels, as @ohmman pointed out. You are going to have to be very careful regarding your tongue weight. I believe the hitch Tesla supplies with the Tow Package option has a max tongue weight of 350 lbs, which is below what it should be towing that much weight (general rule is tongue weight should be 10 to 15% of tow weight). I believe you should use a Weight Distribution hitch for that much tow weight,and the Tesla hitch does not do well with WD based on @ohmman’s experiences which he has posted about. He switched to a Draw Tite hitch with WD.

    Honestly, I don’t think an X is the appropriate vehicle to tow that much weight. I say this reluctantly, as I am one of Tesla’s biggest fans.
     
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  4. j-rho

    j-rho Member

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    Certainly it wouldn't be ideal for towing what I have, but the tow mileage would be not that great (maybe 2-3k mi/year - 2-3x 800 mi round trips, 2-3x 200mi trips). Mostly up/down highway 5, where there's plenty of SCs. Would rent a truck for longer hauls. The other 10k+/yr would be normal driving and road trips with the family.

    I haven't seen any kind of payload rating for the X; often that's the traditional number people overrun first. On the plus side I'm looking at a 5-seater and when towing would be by myself without much stuff in the car.

    One thing I think, given lower speeds when towing with this rig, is the traditional 10-12% tongue weight guidance is probably more conservative than is needed. In the EU, 4-7% is more the norm; some of it has to do with litigiousness, but it also has to do with the lower speeds they pull:
    https://jalopnik.com/tow-me-down-1609112611/1609771499

    Per the physics, with a 50-55mph normal speed, not ever really exceeding 60, one could take a lighter approach (<10%) to tongue weight and still probably be fine. So I'd target 400-450, and not use weight distribution. Been looking at the beefier draw-tite style hitch that replaces the rear bumper, over that weird bearing adapter thingy.

    I've got one of these hitches with the built-in scale:
    Weigh Safe 2-Ball Mount w/ Built-In Scale - 2" Hitch - 4" Drop, 5" Rise - 10K Weigh S
    [​IMG]

    With a car trailer it's relatively easy to tweak tongue weight by rolling the car a few inches forward or backwards on the trailer.

    The efficiency question is the interesting one, even if it's theoretical. I've seen in some places graphs of efficiency vs. other variables, like power draw. While the smaller motor is likely more efficient at cruise and normal use, I wonder how they compare at 2-3x normal cruise draw. It seems possible there'd be a place in their respective curves where the larger motor is actually a little more efficient? Maybe not?

    Buddy of mine got a P100D with the 20" wheels recently, so it's possible, though I don't know if there's any kind of cost break.
     
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  5. AndreyATC

    AndreyATC Member

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    P or not, There is no such thing as default wheel option.
    All Xs come with 20-inch silver wheels
    22s is $5,500 option
     
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  6. ecarfan

    ecarfan Well-Known Member

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    ”Probably” being the key word. The risk of too little tongue weight is uncontrollable trailer sway resulting in a serious accident and injury not only to you but to other drivers on the road with you. Why take that risk?

    I commend you for using a Weigh Safe hitch. I also have one for towing my trailer which has a total weight of less than 2,300 lbs. I make sure my tongue weight is at least 10% of that figure but no more than 15%.
     
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  7. j-rho

    j-rho Member

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    I see risk more as shades of gray, not on and off. What's safe and sound in one circumstance (experienced and well-rested driver, major highway, little traffic, no weather) might be quite unsafe in another (fatigued and less-experienced driver, 2-lane highway with semi trucks, heavy gusting crosswinds). Slowing down pretty much always makes things safer, though in some situations a big speed differential to the rest of traffic can be its own hazard.

    A few weeks ago I played around with tongue weight on an 800 mile round trip. Towed one way with about 8.5%, the other way with about 11%. My current tow vehicle weighs about the same as a Model X, but has a longer wheelbase (pickup truck).

    The lighter tongue weight was more comfortable, but above 72-ish, I started sensing a little "wigglyness". I say this as someone with ~100k miles of incident-free towing experience with many different loads/trailers. As I was in CA going 65mph was no trouble (less illegal too) and at that speed it was perfectly fine in those conditions.

    I suspect with much lower (50-55mph) speeds and shorter hitch-to-rear-axle distance will more than make up for the Tesla's shorter wheelbase. Only one way to find out, hope to do so soon! :)
     
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  8. tpham07

    tpham07 Active Member

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    I wouldn't go with the P option. "Performance" parts sounds like they would wear faster and cost more to replace.
     
  9. j-rho

    j-rho Member

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    If you drive it hard I'd expect stuff like tires and brakes to wear out faster with the ~50% extra power, yes. But when loaded heavy, the P car would seemingly be operating further from its capability ceiling?

    For instance, let's say we're climbing a hill, and to maintain desired speed:
    An X non-P needs to use 30% of its capability
    Given the bigger motor and 50% more oomph, the P is only using 2/3 of that, or 20% of its capability

    With a trailer in tow, to maintain speed the power levels needed might be doubled such that,
    The non-P is using 60% of its capability
    The P is only using 40% of its capability

    Again in the world of ICE towing, it is often found that smaller engines and things will wear out faster when loaded nearer their capacity for long periods of time. This is why burly semi truck motors can go a million miles between rebuilds.

    Not saying this necessarily translates to EVs or Teslas ... only that my personal common sense indicates a more robust drivetrain might be somewhat less "stressed" by the additional burden of a trailer. Also not saying that this would necessarily equate to better (or even equal) range when towing. Interesting to ponder though! :)
     
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  10. tpham07

    tpham07 Active Member

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    I get what you're saying, but I think EV motors are difference from ICE engines. Maybe you are correct P-models aren't as stressed towing as non-P models, but for the $40k price difference, I wouldn't spend that much unless you were planning on utilizing the main benefit of a P-model, which is hilariously fast acceleration.

    But if cost is no concern, just go for the P. That being said, with towing, every Wh/mi extra consumption drastically reduces energy. So if you want maximum efficiency in terms of range, go with the regular non-P.

    my 2 cents. :)
     
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  11. j-rho

    j-rho Member

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    Done some searches, no luck - does anybody know, do the P models have bigger coolers? Is all the extra weight in that bigger rear motor?
    Anybody hit low-power-mode or other overstress type issues when towing? The range reduction is a known :)
    I've seen videos of Teslas on track, they usually go into a sort of limp mode after 30-40 seconds, can't sustain high output very long. Would be a bummer to have that happen when pulling up a hill or something.
     
  12. ecarfan

    ecarfan Well-Known Member

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    That’s not a problem with the Model X.

     
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  13. j-rho

    j-rho Member

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    Haha yep, just like my current tow vehicle can pull the space shuttle: https://jalopnik.com/5951454/how-a-5600-pound-toyota-towed-a-292000-pound-space-shuttle
    Pretty sure a dude on a bicycle could pull them too, with the right gearing :)

    The concern is around an extended pull, clearly things can handle short fun sprints. My worst case might be southbound up the Grapevine on a hot day. Based on what I’ve seen, the climb with trailer might require 1500 kWh/mi for 8-10 miles. Over that length of time the concern would be heat soak of the motors or electrical components. If they can’t shed heat faster than it is being produced, at some point things will go into a thermal protection mode (e.g. overheat).

    Doesn’t seem like this has happened to anyone yet, so perhaps an unfounded concern.Teslas do overheat within a minute or so when driven hard on the track so the possibility exists.

    After extensive searching, couldn’t find any evidence the P model possesses superior cooling capabilities to the regular X100 ... pulled the trigger Saturday on a regular 100, slated for late June delivery. Hope to start adding some travelogues to the collective here later in the year.
     
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  14. idoco

    idoco Member

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    MX90D

    Tin Poodle: Continental divide
     
  15. DMRACING98

    DMRACING98 New Member

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    D1640CBD-AD16-48A3-A059-0A4283734D4F.jpeg 9C7842AF-A2C4-4FF8-81C3-57349CF3C400.jpeg
    I had to sell my taller trailer (102” total height) and go with a low profile version (81”) to pull our race car. It pulls like a dream and much better on range.
    MX100D
     
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  16. j-rho

    j-rho Member

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    Looks nice man! What do you pull in there, do you know the total weight?

    Just got my MX last weekend (Solid delivery, car, and first weekend), can't wait to try towing with it. Last year I bought a smaller and lighter trailer with the intention of towing with an SUV (old vs. new):
    [​IMG]

    Still pretty big though:
    [​IMG]

    Won't try going out of state but I hope to be able to make one of my in-state races that's about 400 miles each way, plenty of SCs on the route (up/down 5 in CA).
     
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  17. Yinn

    Yinn Active Member

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    What trailer is that and what are the specs? It's a good looking one, I've been wanting to upgrade to a dual axle but they all seem to be so heavy!
     
  18. DMRACING98

    DMRACING98 New Member

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    The trailer is 7 x12 with extra 3 foot with the V nose. It’s dry weight is 2013 lbs. We pull a Legends race car and all tools that go with it. In total loaded it’s around 4,600 lbs. We live in Colorado and sometimes race in Vegas. Going up and down the Rockies is a breeze. Obviously, making it from supercharger to supercharger is the goal. So far even pulling at 70 or so has not been an issue. Green River to Richfield is the biggest hurdle. Let me know what other information you would like.
     
  19. spectrum

    spectrum Member

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    At that rate, your 100 kWh battery would only take your car about 350 feet from 100% SOC to 0% :rolleyes: Please do not make false claims. A non-performance Model X can easily pull a 5,000 pound trailer uphill at highway (passing) speeds. It's not a matter of performance or even gearing. The weight limit endorsed by Tesla is more for the frame rigidity and for stability control reasons.
     
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  20. TexasTeslaRacing

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    Our 100D tows like a champ. Better than any SUV like a Tahoe or Suburban. Ease of towing it not the issue, it’s range. We tow a 4,500 travel trailer and at 65mph expect 110 miles of range on flat highway, no wind. Our trailer does not have good aero. Also, add a weight distribution hitch.
     

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