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Smart Air - Efficiency gained at highway speeds?

Discussion in 'Model S: Ordering, Production, Delivery' started by chriSharek, May 9, 2015.

  1. chriSharek

    chriSharek Member

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    What is the efficiency gained by lowering the car at high speeds? Anyone know? Is it 1%, 2?

    I'm ready to give up the air and go with the coils if I can get into an 85D instead of the 70D fully loaded. Any other thoughts on that?
     
  2. jerry33

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

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    It totally depends on the speed. The faster you go the more effective it is. However, there's no real data on how much because it's very hard to remove all the variables and just test for the ride height. The main reasons to get air are the clearance at low speeds and the ride. In general, people get coils because they want road feel and air for comfort and clearance.
     
  3. DavidB

    DavidB Aug 2013 S85

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    I'm biased, I suppose, but I'd hate to give up the air suspension. Even if there is no efficiency gain, the air suspension allows you to raise the suspension when you are driving in rutted roads or over road humps.
     
  4. kuttakamina

    kuttakamina Member

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    Bjorn nyland did a video, and the gain was less than 1%
     
  5. Todd Burch

    Todd Burch Electron Pilot

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    With 35,000 miles on air and 13,000 miles on coils, I agree any efficiency gain is imperceptible given all other variables. Don't use that as your purchase criteria.
     
  6. ChadS

    ChadS Petroleum is for sissies

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    I have the air suspension, and while I like it...it's just not that big of a deal. If I buy another one, I will likely get coils. I had a loaner with coils once and it was just fine. There could be a situation where changing the ride height could help, but there could also be a situation where more range helps. I'd favor the larger battery, but of course you are the one that has to look at your likely driving habits to see what would help more.
     
  7. Cyclone

    Cyclone Active Member

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    I was agnostic about air suspension vs. coils. If ordering new, I would get coils, but I wasn't going to ignore a car if it had air (I was looking at inventory cars too). I ended up with a CPO with air. I'll be fine with it on way or another. Btw, others here (including @tliving) have coils in the snowy NE have no issue - they even have RWD. As I have said to a few others, you can't make a wrong choice as long as your car starts with five letters... T-E-S-L-A.
     
  8. Todd Burch

    Todd Burch Electron Pilot

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    The reason coils aren't a problem with ride height is because the fixed height of a coil car is higher than the normal height of an air car.

    I scraped bottom 3 or 4 times in my air suspension car. I have never scraped bottom in the coil car.
     
  9. taurusking

    taurusking Member

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    I had to get a loaner car since my car was at the service center last weekend. The loaner had air suspension and I liked the smooth ride. However after driving for long distance there was not much difference and on uneven roads coil was better. However like many said before don't base your decision on the coils or air suspension. Go with what you like.:smile:
     
  10. Andyw2100

    Andyw2100 Well-Known Member

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    #10 Andyw2100, May 12, 2015
    Last edited: May 12, 2015
    Lowering at what speed? And then driving at what speed?

    Edit: Though I didn't think I'd be ale to, I found the video, and will watch it. For anyone else interested, it is here: Tesla Model S energy consumption normal vs low suspension - YouTube

    And there's another one, at higher speed, here: Tesla Model S normal vs low suspension at 160 kph/100 mph - YouTube


    What speed do people generally set as the speed to move to "low"? 55? 60?

    Also I have checked the manual, and can't find an answer to this: at what speed will the car raise back to normal? Is it just the same speed? So, for example, if I set the car to change to low at 60 MPH or higher, does it automatically move back to normal ride height when I slow to 59 MPH?

    Thanks.
     
  11. Barry

    Barry Member

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    I have mine set to go Low at 65+ mph. It seems to go back up to Normal at about 50 mph.
     
  12. jerry33

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

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    I set mine at 50 mph.
     
  13. Andyw2100

    Andyw2100 Well-Known Member

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    Thanks, guys.

    Jerry--At what speed do you think your suspension raises back to normal?

    Thanks!
     
  14. jerry33

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

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    I haven't watched it carefully, but from what I've seen it raises as soon as you go less than 50 mph. So I suppose you'll save a bit of energy by setting it at 60 if the traffic speed during your commute oscillates between 45 and 55. You could also set it at always low, but then you have to be far more careful about speed bumps and such. Mostly I don't worry about this as I don't think the compressor uses all that much energy.
     
  15. Blu Zap

    Blu Zap Grinning member

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    Air suspension is lots more valuable than the lowering at speed. I can't imagine living without it. Driveways, speed bumps, parking lots where it get raised, mostly automatically through GPS. Importantly clearing curbs and parking wheel stops.

    I do set my lowering at 70 mph. It goes back to standard around 45-50 mph. I don't have to think about it. It lowers on the freeway and goes back to standard when i take the off-ramp. Bjorn did do a test that showed around a 1% range improvement to lower the car at highway speed. Not a big deal around town. But on a long range trip with Superchargers, that would make a difference, since I tend to speed over the EPA rated range formula. (290 Wh/Mi.) I need all the help I can get.
     
  16. 100thMonkey

    100thMonkey Member

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    we did comparison test drives when trying to settle on which version of the D we were upgrading to. I came close to going with coil suspension after reading people's reviews but I decided to stick with air because I could tell a distinct body roll with the coil springs going into curves. I guess I've gotten spoiled driving air the past couple of years, you feel so planted. originally I had concerns about the long term costs of maintenance with the air but it seems that there just have not been issues so far, perhaps because Tesla decompresses the system when the car is off.
     
  17. chriSharek

    chriSharek Member

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  18. brianman

    brianman Burrito Founder

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    RTFM:
     
  19. Andyw2100

    Andyw2100 Well-Known Member

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    #19 Andyw2100, May 14, 2015
    Last edited: May 14, 2015
    You know what? I did RTFM. And I said that upthread.

    Show me where in what you posted the manual indicates at what speed the car raises back to normal, after having been lowered. When you can't, I'll accept your apology.



    Edit: This is what I had written:



    And then there were answers to that question that varied greatly:

     
  20. chriSharek

    chriSharek Member

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    The 1% equates to 2.7 miles on the 85D. Come on!? I'm torn because the long-term costs with the air are pretty significant. I'm convinced on the 19"s because they provide 3% more than the 21"s PLUS they last longer AND are cheaper to replace. But 3% is almost 10 miles of range on the 85D. That's significant. I don't see the 1%/2.7 miles would really make a difference.
     

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