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Mirrors folded for higher mileage

Discussion in 'Model S: Driving Dynamics' started by scottm, Mar 10, 2017.

  1. scottm

    scottm Active Member

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    Sometimes late at night on open quiet hiways when I'm cruising and want to get highest range possible.. one of the buttons I reach for mirror folding. I figure it reduces frontal area a bit and probably helps.

    (wikipedia) Side mirrors[edit]
    Side mirrors both increase the frontal area of the vehicle and increase the coefficient of drag since they protrude from the side of the vehicle.[10][11] In order to decrease the impact that side mirrors have on the drag of the vehicle the side mirrors can be replaced with smaller mirrors or mirrors with a different shape. Several concept cars of the 2010s are replacing mirrors with tiny cameras[12] but this option is not common for production cars because most countries require side mirrors.
     
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  2. Haxster

    Haxster Member

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    Obviously a safety concern and in California at least, a possible "fix-it" ticket if pulled over.

    I seem to remember that Tesla wanted to use cameras on the MS to reduce drag but ran into legal issues with this at the time.

    It's possible that the fender-mounted cameras on HW2 vehicles could replace the side view mirrors in the near future.
     
  3. SabrToothSqrl

    SabrToothSqrl Active Member

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    Last set of rear tires... about 8,000 miles ;)
     

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  4. emchen

    emchen Member

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    I used to do that but noticed increased noise when the mirrors were folded. I hypothesize that it is due to increased turbulent air-flow and a decrease in laminar flow. It seems to me that the decreased frontal area associated with folded mirrors is offset by increased angularity of the surface facing wind resistance, and an overall increase in vehicle drag.
     
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  5. scottm

    scottm Active Member

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    #5 scottm, Mar 10, 2017
    Last edited: Mar 10, 2017
    I do hear a bit more rumble off a folded mirror and wondered the same thing...
    But the mirror still has a nice torpedo shape cutting into the wind even when folded.

    Have you noticed these weird bulges on newer vehicles that pop out around the front headlamps lately? Toyota's are famous for these. At first I just thought "ugly style" but found out they're functional - they push out an air pocket that lets the side mirrors slip through with less turbulence.

    Found a good article on the topic:
    6 reasons why I can't wait for cameras to replace rearview mirrors - Roadshow

    "wing mirrors contribute between 3 to 6 percent of aerodynamic drag"

    I test drove Honda Accord couple years ago, it already has passenger side mirror camera under the wing mirror... once you see the effect on the center screen versus looking at the glass mirror, you understand there's really no need for the mirror over there anymore, except for ... laws waiting to catch up.
     
  6. sdorn

    sdorn Director of Awesome

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    I haven't tried this on the Tesla before, but on my other cars the folding mirrors automatically fold out at a certain speed (like 15 mph or so).
     
  7. Pezpunk

    Pezpunk Member

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    compromising safety for negligible (possibly zero) mileage gain seems like a bad decision to me. i wouldn't even consider it unless someone can prove significant gains.
     
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  8. Drewflux

    Drewflux Member

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    Hmmm might be time to bust out the go-pro and wool tuff test. I agree that folding them in is most likely worse.
     
  9. n2mb_racing

    n2mb_racing Member

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    How do you fold the mirrors in while driving? Haven't seen a button for that...
     
  10. thimel

    thimel Member

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    It is on the driver's door between the buttons that select which side mirror you want to adjust.
     
  11. Gwgan

    Gwgan Almost a wagon

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    The X works this way but on S loaners I have tried it (on stretches of empty highway) and did not see a difference while watching the energy graph. Purely annnecdotal.
     
  12. jerry33

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

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    On the S, if you look at the mirrors, they are more aerodynamic when extended--and the amount they go in isn't very much, so the frontal area isn't reduced by any appreciable amount. I'd suggest that your observation is correct.
     
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  13. kort677

    kort677 Active Member

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    I'd just add that the OPs idea comes under penny wise and pound foolish.
    the savings he might garner with his folding the mirrors is minimal and the dangers he's introducing make driving the car far less safe
     
  14. sorka

    sorka Active Member

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    I've tried this on my 130 mile commute and it appeared to make no measurable difference except for increasing the wind noise so if anything I suspect that it would worsen fuel economy as this is not the shape they optimized for in the wind tunnel.
     
  15. EarlyAdopter

    EarlyAdopter Active Member

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    Anyone try adding winglets to the side mirrors?
     
  16. Todd Burch

    Todd Burch Electron Pilot

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    I've tried this too and have found the poorer drag coefficient to offset the reduction in frontal area to the point where I can't see a measurable difference, and the extra noise just isn't worth it. If cameras were used and the housing were an efficient bullet shape you'd probably see a minor difference at highway speeds, but as it is I don't see a difference.

    And let's be honest, if it's dark and you're on the interstate in some rural area and there's no traffic around, I don't see side mirrors as contributing to safety at all. Let's not go overboard with the safety police...
     
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