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Is an AWD Model S Necessary?

Discussion in 'Model S: Driving Dynamics' started by NigelM, Jun 15, 2012.

  1. NigelM

    NigelM Recovering Member

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    Could be an interesting discussion why anyone would want/need an AWD Model S when they could buy a Model X on the same platform, anyone want to start a thread in the S or X section?
     
  2. richkae

    richkae VIN587

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    Thread move bait:
    A Model S will have more range than a Model X with the same battery. Some people don't need bigger.
     
  3. Trnsl8r

    Trnsl8r Blue 85kwh since 12/8/12

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    And... an AWD Model S will have more range than a RWD Model S... due to more regen.
     
  4. MitchL

    MitchL S#945

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    Sure about that?

    The way I look at it is: the total amount of kinetic energy in the car to be converted back into electricity doesn't really change for AWD (assuming similar weight, speed), so I would not expect regen to be significantly different.

    I suppose you could have much more aggressive regen with AWD, but at some point it's too much, right?

    /Mitch.
     
  5. Trnsl8r

    Trnsl8r Blue 85kwh since 12/8/12

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    Pretty sure I read somewhere that the AWD version of Model X would have better range due to being able to regen-capture energy on both axels, but now I can't find the link...
     
  6. rolosrevenge

    rolosrevenge Dr. EVS

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    I would buy an AWD Model S over a Model X. It adds additional performance and handling, especially in the snow, and the S will be cheaper than the X with the same sized pack. It's like my A6 Quattro, definitely not an off road vehicle, but I bought it for the AWD for snowy and slushy conditions.
     
  7. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    This is my thought too.

    Regeneration is better than throwing away the energy as heat the way that friction brakes do, but there are losses because the motor/generator and inverter heat up, so regeneration is not as good as using the kinetic energy to glide whenever possible. When gliding only the resistance of the bearings, tires, and wind steal the energy. I haven't seen numbers for the Tesla, but for the Prius only 33% to 50% is captured by regeneration (and things have to be perfect to approach 50%). I suspect the Tesla will capture more because the battery can take a higher level of charge, but every time you convert energy from one form to another there are losses. I'd love to see some actual measurements of this.
     
  8. Robert.Boston

    Robert.Boston Model S VIN P01536

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    Remember with the Prius, you can only access regeneration through the brake pedal. It would take a lot of skill to maximize regen without engaging the friction brake. This will not be an issue on the Model S. My recollection is that Roadster owners claim ~80% efficiency on regen.
     
  9. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Regeneration also happens when you let your foot off the gas. It's not as strong of a regeneration as Tesla, but it's [expletive deleted] annoying because you have to educate your foot to press just the right amount so that you aren't regenerating--this takes a lot of practice to get right. I'd rather have the Prius' regeneration only on the brakes.

    Disk brakes always touch the rotors so there is always a certain amount of friction braking. Not a lot of skill is required to get the most regeneration--just a bit of planning ahead so you don't roar up to the stop light and then stomp on the brakes like so many drivers do. However, it's better to avoid both the regeneration and the friction braking. In the Prius this is done by just holding the gas pedal at the point where there is neither power nor regeneration occurring. Additional instrumentation helps with this, as does a lot of practice.

    That is a number that I was looking for.
     
  10. bonnie

    bonnie Oil is for sissies.

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    So who wants to see if they can bring this new thread back on topic? Anyone?
     
  11. AnOutsider

    AnOutsider S532 # XS27

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    Sure. Wasn't Tesla (and/or folks here) touting that even a rear wheel drive EV with their software was better than a traditional AWD vehicle? If so, and there is no range increase (as traditionally AWD has been a fuel economy killer -- though that paradigm may change with EVs), what would be the benefit other than performance (which for many, myself included, that alone is important)?
     
  12. jerry33

    jerry33 S85 - VIN:P05130 - 3/2/13

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    Okay, here goes:

    I don't see AWD being necessary for the Model S. I've never missed AWD on the Prius due to the traction control (TC) and vehicle stability control (VSC) and good severe service tires. On ice days I'm usually the fastest vehicle out there and the 4x4s I see are typically in the ditch. I've never had a problem in the blizzards I've driven through either. AWD was a good item before VSC but now it's just an extra complication except in off road vehicles. It's also one of those things where the logic goes like this: "If I get in trouble with AWD it's in spite of having AWD, if you get in trouble without AWD it's because you didn't have AWD".

    The one place AWD would be an asset is on the track where all four tires are delivering power. So if you plan to race your Model S, then get AWD--otherwise it's a cost and maintenance item easily avoided and won't be missed.
     
  13. bonnie

    bonnie Oil is for sissies.

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    When I lived in snow country, the similar saying was "All 4wd does is allow you to get stuck in places harder to get you out of."
     
  14. cinergi

    cinergi Active Member

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    Obvious snow advantages aside, I like AWD because of the additional grip during hard acceleration, especially from a stop and turning onto a street, especially uphill. And you can get more performance for two reasons: extra grip and extra motor. I would do it. And I think it helps sell the car better, too. Especially in areas like here in the NE US because RWD is generally a big no-no for snowy climates. I have to convince people RWD on a Tesla is really good even in the snow. I'd rather not have to have that conversation :smile:
     
  15. doug

    doug Administrator / Head Moderator

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    Is an AWD Model S Necessary? No.
    Is there a market for it? Definitely!
     
  16. GSP

    GSP Member

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    Is an AWD Model S *necessary?*. Of course not. Only food, water, and shelter are necessary, and perhaps survival itself is not "necessary."

    Would an AWD Model S be a worthwile and desirable addition to Tesla's product line? Absolutely! Some customers do not like SUV's size, handeling, and extra mass. However AWD can provide more traction and performance. Tesla cost for product development and tooling to bring this to market would be reasonable as well.

    GSP
     
  17. ljbad4life

    ljbad4life Member

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    I always thoughts that for the performace model S they would include AWD. if having RWD you get 4.4, i'm sure AWD can get that time down closer to (or maybe under) 4 seconds. IMHO I don't think that AWD in the model s would kill the range or add to much weight, all you need is another motor.
     
  18. daniel

    daniel Active Member

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    Definitely true of my old CJ5 Jeep. I will never forget (nor will my sister) the day we spent an hour shoveling snow to extricate it. But OTOH, some folks live where they would not get in and out at all with out AWD. The thing is, with AWD or 4WD, you need to know what the vehicle really is and is not capable of, and you need to understand, e.g., that it helps you to go, but does nothing to help you stop.

    I would not call it "necessary" that there be an AWD Model S, but the S and the X are very different cars, with different target buyers, and there will definitely be a market for an AWD S. I think the X is bigger than the S? And the S is already too big a car for me. My old '89 Civic wagon was the perfect size for me. The Prius is bigger than I need. And although I've (obviously) never driven an S, I am not comfortable driving cars that big. If I was choosing between the X and the S, I'd definitely prefer the S, and if I needed AWD I'd not want to have to take the bigger car to get it.
     
  19. Jason S

    Jason S Model S Sig Perf (P85)

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    This is the reason for AWD Model S performance. Lose most of the frunk and gain some incremental performance.

    In addition California rules for snow let AWD vehicles go without chains in conditions that require chains (by law, not necessarily by physics) for just 2 wheel drive. It would be useful for some people in the snowy parts of CA.
     
  20. richkae

    richkae VIN587

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    I don't believe additional regen from AWD would extend range. It is very very rare that I need more regen.
    I believe that the AWD version will have slightly more drivetrain drag, and that it will hurt range by a small amount.

    If there was an AWD Model S, I would want to see a proper performance comparison done in the snow.
    1. 2WD Model S with all-seasons
    2. 2WD Model S with real snow tires
    3. AWD Model S with the same snow tires
    4. AWD Model S with the all-seasons
    I think the traction control in the 2WD Model S ( with proper tires ) would make its performance very close to the AWD.

    If the range penalty of AWD is 5% and the snow performance difference is insignificant, then I would stick with 2WD.
     

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