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Windows in closed position - How pertinent is this tip?

Discussion in 'Non FIAT Cars and two wheelers' started by sine04, Mar 23, 2014.

  1. sine04

    sine04 Regolare

    Messages:
    275
    Mysore/Bangalore, Karnataka.
    Mysore/Bangalore, Karnataka.
    Fiat Enthusiast
    While browsing through a handout given by Ford, I came across this tip to increase FE-

    "During long drives always keep the windows in a closed position."

    Although there may be an increase in FE, won't the corresponding usage of AC ( I'm assuming that the user isn't resigned to either bake or suffocate! ) negate the increase?
    Can anyone shed some light on the veracity of this claim or the logic behind it?

    Sent from my Nexus 5 using Tapatalk

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    Last edited by a moderator: Mar 24, 2014
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  2. PaddleShifter

    PaddleShifter Staff Member Janitor

    Messages:
    2,702
    Chandigarh
    Grande Punto 1.3
    Even the Eco:Drive by FIAT says the same. Reason is that keeping the windows clossed/glass uprolled is better for aerodynamics and thus the resistance reduces. Another tip that I learnt was to keep cabin temperature at 23 or more for cars having auto AC.

    BTW, ours is a tropical climate and thus we need AC more often as compared to western countries.
    1 person likes this.
  3. asimpleson

    asimpleson Esperto

    Messages:
    3,161
    Heptanesia
    Linea 1.3
    Apart from the facts mentioned by Paddleshifter, there is also the benefit of travelling dust free. That is assuming the AC is working well. As far as fuel efficiency is concerned, it will certainly improve as I think, it will help lower the air drag to some extent. I have better acceleration on highways with all windows closed. So it is true, I figure.
  4. sine04

    sine04 Regolare

    Messages:
    275
    Mysore/Bangalore, Karnataka.
    Mysore/Bangalore, Karnataka.
    Fiat Enthusiast
    So to summarise, even with AC running full time, on long journeys, we will still end up getting better FE figures due to the reduced drag resulting from rolled up windows?
    But, does it hold good even for cars that travel at 60-80kmph? Will air drag still play that big a factor?

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  5. naruf1

    naruf1 Amatore

    Messages:
    175
    Namma Bengaluru
    Thanks for bringing up this topic!

    According to this URL it says the cut of speed is around 64 kmph. It also says that the amount of drag induced is exponential with speed. i.e. if speed doubles the drag increases by four times.

    HowStuffWorks "When to Roll the Windows Down"
    3 people like this.
  6. sine04

    sine04 Regolare

    Messages:
    275
    Mysore/Bangalore, Karnataka.
    Mysore/Bangalore, Karnataka.
    Fiat Enthusiast
    @naruf1- Nice find! The bottom line though seems to be inconclusive and leaves it to our discretion! :)

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  7. asimpleson

    asimpleson Esperto

    Messages:
    3,161
    Heptanesia
    Linea 1.3
    I would say it is not quantified precisely but not that inconclusive. :p

    Yes, discretion wise AC would still make better choice especially in our tropical climates with added benefits of reduced drag.


    :p heartsent for our mutual benefit .. !
  8. Ganges

    Ganges Esperto

    Messages:
    3,176
    Driver Seat _/
    :
    Grande Punto 1.3
    For me,
    windows are rolled up only when there is dust and tire noise or road noise is annoying.Do we really think there is air drag effect on `FE that too on indian roads :D . i would always like to see the Avg Speed after a long highway trip.
  9. asimpleson

    asimpleson Esperto

    Messages:
    3,161
    Heptanesia
    Linea 1.3
    Get your point but air drag effect is very much there and does affect FE though not that pronounced. Should we put it under a microscope is a different discussion. There is a whole section related to this which falls under the topic of Automotive drag coefficient.

    More information in this link — Automobile drag coefficient - Wikipedia, the free encyclopedia

    http://www.teamfiat.co.in/non-fiat-...ts-how-they-help-improve-fuel-efficiency.html
    2 people like this.
  10. Ganges

    Ganges Esperto

    Messages:
    3,176
    Driver Seat _/
    :
    Grande Punto 1.3
    Agreed,thats the initial design of the product in terms of aerodynamics of vehicle.Giving a thought on drag effect after(closed windows) the design of product dont see any major difference.The case might have been different if it was on a race track or on autobahn.
    Lets put it in this way "Technical White papers are always made in the worst case scenarios " :D

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