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TACC drafting?

Discussion in 'Model S: Driving Dynamics' started by Saghost, May 2, 2016.

  1. Saghost

    Saghost Active Member

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    I know there's been a fair amount of discussion in the past about the value and safety of drafting during long trips, but it seems to me like TACC/AP changes things.

    Drafting a semi while in TACC shouldn't add any real risk for either one of you, provided the semi doesn't hit something or throw a tread (though it might make the semi driver nervous since he won't know the computers are protecting you.)

    It'd be interesting to see how much drafting in the various distance settings reduces energy consumption over time - and if you have a flat place and a semi that's going at a fixed pace, it seems like the energy usage center console screen could show you the savings quite easily.

    Has anyone done any experimenting with this?
    Walter
     
  2. kort677

    kort677 Active Member

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    I did a lot of drafting in KS headed west on I70, I set the TACC at 2 or 3 and stayed alert. drafting could add significant miles to your range (20+%). that stretch is a constant upgrade and prone to severe headwinds.
     
  3. Edmond

    Edmond Permanon

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    You have to get so close to draft that I don't do it. If you open your windows and still have significant wind noise, you aren't drafting.

    Not to mention, it makes the trucker mad.
     
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  4. Saghost

    Saghost Active Member

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    I've been told on various occasions that it annoys them, but I'm not sure why it should in the described circumstances.

    They'll get a slight improvement in economy too, and haven't gotten any additional risk. I think they are usually worried about being rear ended, but TACC will prevent that.
     
  5. kort677

    kort677 Active Member

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    that has not been my experience. I find that even at 2-3 car lengths back I see better wh/miles and if you "help" the truckers by throwing blocks so they can change lanes there usually isn't a problem.
     
  6. Khatsalano

    Khatsalano Member

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    I understand the benefits of drafting. But unless it truly saves you money or time by avoiding a charging stop altogether, why would you take so many rock chips in the face?? Look closely at your nosecone and your hood ... that isn't dirt. It's your paint all chipped up. :)

    - K
     
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  7. Saghost

    Saghost Active Member

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    Valid point.

    Of course, I was already planning on putting a protective film on the car. :)
     
  8. mmccord

    mmccord Member

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    This is a fantastic way to improve your wh/mi. I'm a big fan of finding a truck doing ~75mph and setting TACC distance to 1.
     
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  9. supratachophobia

    supratachophobia Active Member

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    Mythbusters confirmed this. Even at a safe 150ft it's noticeable. Using TACC with a low number will easily get you 20% in most circumstances.

    I would like feedback from a truck driver on if blocking is helpful.
     
  10. beantobe

    beantobe Member

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    Interesting to think about the effect drafting could have on the car. From a safety standpoint, it should not be done. (I've taken a few mandated driving classes and the instructors always cite studies on how even with a quick reaction time, the car behind you or on the side of you cannot anticipate quick movement and the likelihood of an accident goes up significantly.)

    I have no evidence to back this up except my own experience cycling: when drafting behind a larger rider, I have to be a few inches from their wheel to be in their slipstream. (Obviously this distance is different while driving) Even when cycling, it takes quite a bit of experience to do this safely and perfectly. I can't imagine how someone could do this safely in an uncontrolled environment like a freeway. But if there is a safe way to do it (without pissing off the big rigs) count me in!
     
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  11. kort677

    kort677 Active Member

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    does your bike have TACC?
    the TACC reacts to a change in speed as fast as I could, and I am able to react to the TACC reaction. I did this for a couple of hundred miles on lightly traveled roads. It may not work so well in congested areas.
     
  12. scottf200

    scottf200 Active Member

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    Posted the video link here: Drafting big rigs saves a minimum of 10 percent range
     
  13. beantobe

    beantobe Member

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    Is TACC supposed to react faster than drivers? Honest question.

    Of course the cycling analogy is not a perfect one. Everyone has a different threshold for risk. Drafting a truck happens to be too risky for me. For others, it may feel very safe. I tend to think of worse case scenarios like a deer jumping out in front of truck.

    I think the myth busters did an episode on cars or trucks drafting. I honestly can't remember their conclusion.

    There must be some state trooper or physicist on here that can give there input on experience watching people draft or if it can be done safely.

    Does anyone know if it's even legal?
     
  14. beantobe

    beantobe Member

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  15. kort677

    kort677 Active Member

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    have you ever driven a TACC equipped tesla? do you own a tesla?
     
  16. eye.surgeon

    eye.surgeon Member

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    I hope you're a big fan of road rage because you're going to get a lot of it doing that.
     
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  17. ohmman

    ohmman Maximum Plaid Member

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    A related idea is to get a convoy of Teslas (perhaps all headed to Connect or some other event) and get a TACC-drafting caravan going.
     
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  18. beantobe

    beantobe Member

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    Agreed. There is a culture among commercial truckers that is undeniable and more often than not, drafting will aggravate them. I'm not saying that they are justified in responding that way. Whether drafting is good/bad illegal/legal risky/perfectly safe with TACC/without it driving in a way that reduces the chance of aggravating drivers is courteous and usually safer driving.

    I think if we talk about this kind of driving, it's imperative to include some discussion about safety so there is full disclosure and people who might have less common sense understand potential risks.

    We can be driving a car with the best safety technology in world but the closer you get to the back of a truck, the greater your risk. How you measure that incremental increase in risk is very subjective. No one needs to own a Tesla or fully understand or have experience with TACC to understand that.
     
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  19. beantobe

    beantobe Member

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    Like those biker gangs do! That would be a blast.
     
  20. ohmman

    ohmman Maximum Plaid Member

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    Sure, for the lead guy. But for the rest, it would be a breeze.
     
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