Why are hatchbacks and SUVs' rear window vertical, relative to sedans' at around 45°?












1
















  1. I noticed this angular difference while reading these Quora and Reddit posts about why sedans don't have rear wipers, as the aerodynamic reason fails to remove precipitation as efficaciously as wipersn.


  2. Wouldn't a 45° rear window be better for SUVs, to lessen road debris spattering the rear window?











share|improve this question




















  • 2





    Bringing the rear roofline inward to tilt the window would reduce the carrying capacity back there, a primary concern for people buying SUVs is "how much stuff can I get back there?"

    – Patrick Hughes
    3 hours ago











  • A sloping rear window between a flat roof and trunk has the paradoxical property that in a certain speed range, the air flow is UP the window, not down, and air (and dirt) are trapped in an eddy behind the window. I used to have a car where rain water moved up the rear window driving between about 40-60 mph. In that situation, a rear wiper doesn't do anything very useful - it pushes the water down but it immediately flows back up.

    – alephzero
    1 hour ago


















1
















  1. I noticed this angular difference while reading these Quora and Reddit posts about why sedans don't have rear wipers, as the aerodynamic reason fails to remove precipitation as efficaciously as wipersn.


  2. Wouldn't a 45° rear window be better for SUVs, to lessen road debris spattering the rear window?











share|improve this question




















  • 2





    Bringing the rear roofline inward to tilt the window would reduce the carrying capacity back there, a primary concern for people buying SUVs is "how much stuff can I get back there?"

    – Patrick Hughes
    3 hours ago











  • A sloping rear window between a flat roof and trunk has the paradoxical property that in a certain speed range, the air flow is UP the window, not down, and air (and dirt) are trapped in an eddy behind the window. I used to have a car where rain water moved up the rear window driving between about 40-60 mph. In that situation, a rear wiper doesn't do anything very useful - it pushes the water down but it immediately flows back up.

    – alephzero
    1 hour ago
















1












1








1









  1. I noticed this angular difference while reading these Quora and Reddit posts about why sedans don't have rear wipers, as the aerodynamic reason fails to remove precipitation as efficaciously as wipersn.


  2. Wouldn't a 45° rear window be better for SUVs, to lessen road debris spattering the rear window?











share|improve this question

















  1. I noticed this angular difference while reading these Quora and Reddit posts about why sedans don't have rear wipers, as the aerodynamic reason fails to remove precipitation as efficaciously as wipersn.


  2. Wouldn't a 45° rear window be better for SUVs, to lessen road debris spattering the rear window?








window aerodynamcs vehicle-dynamics






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edited 3 hours ago









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  • 2





    Bringing the rear roofline inward to tilt the window would reduce the carrying capacity back there, a primary concern for people buying SUVs is "how much stuff can I get back there?"

    – Patrick Hughes
    3 hours ago











  • A sloping rear window between a flat roof and trunk has the paradoxical property that in a certain speed range, the air flow is UP the window, not down, and air (and dirt) are trapped in an eddy behind the window. I used to have a car where rain water moved up the rear window driving between about 40-60 mph. In that situation, a rear wiper doesn't do anything very useful - it pushes the water down but it immediately flows back up.

    – alephzero
    1 hour ago
















  • 2





    Bringing the rear roofline inward to tilt the window would reduce the carrying capacity back there, a primary concern for people buying SUVs is "how much stuff can I get back there?"

    – Patrick Hughes
    3 hours ago











  • A sloping rear window between a flat roof and trunk has the paradoxical property that in a certain speed range, the air flow is UP the window, not down, and air (and dirt) are trapped in an eddy behind the window. I used to have a car where rain water moved up the rear window driving between about 40-60 mph. In that situation, a rear wiper doesn't do anything very useful - it pushes the water down but it immediately flows back up.

    – alephzero
    1 hour ago










2




2





Bringing the rear roofline inward to tilt the window would reduce the carrying capacity back there, a primary concern for people buying SUVs is "how much stuff can I get back there?"

– Patrick Hughes
3 hours ago





Bringing the rear roofline inward to tilt the window would reduce the carrying capacity back there, a primary concern for people buying SUVs is "how much stuff can I get back there?"

– Patrick Hughes
3 hours ago













A sloping rear window between a flat roof and trunk has the paradoxical property that in a certain speed range, the air flow is UP the window, not down, and air (and dirt) are trapped in an eddy behind the window. I used to have a car where rain water moved up the rear window driving between about 40-60 mph. In that situation, a rear wiper doesn't do anything very useful - it pushes the water down but it immediately flows back up.

– alephzero
1 hour ago







A sloping rear window between a flat roof and trunk has the paradoxical property that in a certain speed range, the air flow is UP the window, not down, and air (and dirt) are trapped in an eddy behind the window. I used to have a car where rain water moved up the rear window driving between about 40-60 mph. In that situation, a rear wiper doesn't do anything very useful - it pushes the water down but it immediately flows back up.

– alephzero
1 hour ago












3 Answers
3






active

oldest

votes


















3














For the angle of the rear window, vertical is basically for the load volume / carrying capacity, getting things with a high roof line opening.



Well, some sedans or sedans with a hatch-back did have rear wipers...






share|improve this answer
























  • Here's one with a wiper: parkers-images.bauersecure.com/gallery-image/pagefiles/189881/… so you are indeed correct some have a rear wiper.

    – juhist
    3 hours ago











  • @juhist well, I was going to go with the Chrysler Solara or the Sunbeam, but a Vauxhall is proof enough...

    – Solar Mike
    3 hours ago



















0














The reason for the question in the title (why vertical?) is that car has a maximum possible length if you want it to be maneuverable in tight spaces. For example, my Toyota RAV4 hybrid is approximately 4.6 meters long. Quite long, in my opinion. Compared to the Toyota Yaris I used to have, it's much less maneuverable.



If the car was longer, say 5.0 meters long (like Tesla Model X), you couldn't maneuver the car through very tight corners. One of the reasons why I don't have a Tesla Model X (another being its width, third being its price).



Now, Tesla Model X doesn't have a vertical rear window, the window being more like 45 degrees. My Toyota RAV4 hybrid has a vertical rear window.



This means that if you want to transport large objects, a Tesla Model X with its 5.0 meter length is probably approximately as useful as my 4.6 meters long Toyota RAV4 hybrid. Same indoor dimensions at the roof level, much different external dimensions.



Now, would a 45 degree rear window be better? I would say not better, because it would make the car too long externally if it has any useful large object carrying capacity, or make the car's carrying capacity too limited if the external dimensions are sensible.



Am I alone in this opinion? You know, some people actually buy Tesla Model X. I even know somebody who has a Tesla Model X! Personally, I'm happy with my vertical rear window and wouldn't change to a 45 degree window. I'll buy an electric or plug-in-hybrid SUV the day when you can purchase one that has small enough external dimensions, large enough internal dimensions (necessitating a vertical rear window), sensible enough price and made by a reputable manufacturer I can trust.






share|improve this answer































    0














    There are basically two options to reduce air resistance at the rear of the car to a minimum.



    One is to make the rear flat and vertical. That way, the air flowing over the car doesn't create any turbulence until it has "passed" the rear of the car.



    The other way is to make body into an airfoil shape by bringing the roof level down smoothly and raising the floor level at the rear, so the air flow does not separate from the car bodywork. That has been carried to its logical conclusion in experimental solar powered cars (image source: Wikipedia)



    enter image description here



    Introducing a "backward facing step" by having a flat roof, a vertical rear window, and a flat top to the trunk is pretty much the worst of all worlds, aerodynamically. Hence the rear window is sloped to get closer to an airfoil shape.



    In practice, body designs are a compromise between aerodynamic efficiency, functionality and aesthetics - for example a 30-ton truck with a flat rear panel is both functional (to maximize the volume of the cargo space) and aerodynamic, but not pretty!






    share|improve this answer























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      3 Answers
      3






      active

      oldest

      votes








      3 Answers
      3






      active

      oldest

      votes









      active

      oldest

      votes






      active

      oldest

      votes









      3














      For the angle of the rear window, vertical is basically for the load volume / carrying capacity, getting things with a high roof line opening.



      Well, some sedans or sedans with a hatch-back did have rear wipers...






      share|improve this answer
























      • Here's one with a wiper: parkers-images.bauersecure.com/gallery-image/pagefiles/189881/… so you are indeed correct some have a rear wiper.

        – juhist
        3 hours ago











      • @juhist well, I was going to go with the Chrysler Solara or the Sunbeam, but a Vauxhall is proof enough...

        – Solar Mike
        3 hours ago
















      3














      For the angle of the rear window, vertical is basically for the load volume / carrying capacity, getting things with a high roof line opening.



      Well, some sedans or sedans with a hatch-back did have rear wipers...






      share|improve this answer
























      • Here's one with a wiper: parkers-images.bauersecure.com/gallery-image/pagefiles/189881/… so you are indeed correct some have a rear wiper.

        – juhist
        3 hours ago











      • @juhist well, I was going to go with the Chrysler Solara or the Sunbeam, but a Vauxhall is proof enough...

        – Solar Mike
        3 hours ago














      3












      3








      3







      For the angle of the rear window, vertical is basically for the load volume / carrying capacity, getting things with a high roof line opening.



      Well, some sedans or sedans with a hatch-back did have rear wipers...






      share|improve this answer













      For the angle of the rear window, vertical is basically for the load volume / carrying capacity, getting things with a high roof line opening.



      Well, some sedans or sedans with a hatch-back did have rear wipers...







      share|improve this answer












      share|improve this answer



      share|improve this answer










      answered 3 hours ago









      Solar MikeSolar Mike

      18.1k21032




      18.1k21032













      • Here's one with a wiper: parkers-images.bauersecure.com/gallery-image/pagefiles/189881/… so you are indeed correct some have a rear wiper.

        – juhist
        3 hours ago











      • @juhist well, I was going to go with the Chrysler Solara or the Sunbeam, but a Vauxhall is proof enough...

        – Solar Mike
        3 hours ago



















      • Here's one with a wiper: parkers-images.bauersecure.com/gallery-image/pagefiles/189881/… so you are indeed correct some have a rear wiper.

        – juhist
        3 hours ago











      • @juhist well, I was going to go with the Chrysler Solara or the Sunbeam, but a Vauxhall is proof enough...

        – Solar Mike
        3 hours ago

















      Here's one with a wiper: parkers-images.bauersecure.com/gallery-image/pagefiles/189881/… so you are indeed correct some have a rear wiper.

      – juhist
      3 hours ago





      Here's one with a wiper: parkers-images.bauersecure.com/gallery-image/pagefiles/189881/… so you are indeed correct some have a rear wiper.

      – juhist
      3 hours ago













      @juhist well, I was going to go with the Chrysler Solara or the Sunbeam, but a Vauxhall is proof enough...

      – Solar Mike
      3 hours ago





      @juhist well, I was going to go with the Chrysler Solara or the Sunbeam, but a Vauxhall is proof enough...

      – Solar Mike
      3 hours ago











      0














      The reason for the question in the title (why vertical?) is that car has a maximum possible length if you want it to be maneuverable in tight spaces. For example, my Toyota RAV4 hybrid is approximately 4.6 meters long. Quite long, in my opinion. Compared to the Toyota Yaris I used to have, it's much less maneuverable.



      If the car was longer, say 5.0 meters long (like Tesla Model X), you couldn't maneuver the car through very tight corners. One of the reasons why I don't have a Tesla Model X (another being its width, third being its price).



      Now, Tesla Model X doesn't have a vertical rear window, the window being more like 45 degrees. My Toyota RAV4 hybrid has a vertical rear window.



      This means that if you want to transport large objects, a Tesla Model X with its 5.0 meter length is probably approximately as useful as my 4.6 meters long Toyota RAV4 hybrid. Same indoor dimensions at the roof level, much different external dimensions.



      Now, would a 45 degree rear window be better? I would say not better, because it would make the car too long externally if it has any useful large object carrying capacity, or make the car's carrying capacity too limited if the external dimensions are sensible.



      Am I alone in this opinion? You know, some people actually buy Tesla Model X. I even know somebody who has a Tesla Model X! Personally, I'm happy with my vertical rear window and wouldn't change to a 45 degree window. I'll buy an electric or plug-in-hybrid SUV the day when you can purchase one that has small enough external dimensions, large enough internal dimensions (necessitating a vertical rear window), sensible enough price and made by a reputable manufacturer I can trust.






      share|improve this answer




























        0














        The reason for the question in the title (why vertical?) is that car has a maximum possible length if you want it to be maneuverable in tight spaces. For example, my Toyota RAV4 hybrid is approximately 4.6 meters long. Quite long, in my opinion. Compared to the Toyota Yaris I used to have, it's much less maneuverable.



        If the car was longer, say 5.0 meters long (like Tesla Model X), you couldn't maneuver the car through very tight corners. One of the reasons why I don't have a Tesla Model X (another being its width, third being its price).



        Now, Tesla Model X doesn't have a vertical rear window, the window being more like 45 degrees. My Toyota RAV4 hybrid has a vertical rear window.



        This means that if you want to transport large objects, a Tesla Model X with its 5.0 meter length is probably approximately as useful as my 4.6 meters long Toyota RAV4 hybrid. Same indoor dimensions at the roof level, much different external dimensions.



        Now, would a 45 degree rear window be better? I would say not better, because it would make the car too long externally if it has any useful large object carrying capacity, or make the car's carrying capacity too limited if the external dimensions are sensible.



        Am I alone in this opinion? You know, some people actually buy Tesla Model X. I even know somebody who has a Tesla Model X! Personally, I'm happy with my vertical rear window and wouldn't change to a 45 degree window. I'll buy an electric or plug-in-hybrid SUV the day when you can purchase one that has small enough external dimensions, large enough internal dimensions (necessitating a vertical rear window), sensible enough price and made by a reputable manufacturer I can trust.






        share|improve this answer


























          0












          0








          0







          The reason for the question in the title (why vertical?) is that car has a maximum possible length if you want it to be maneuverable in tight spaces. For example, my Toyota RAV4 hybrid is approximately 4.6 meters long. Quite long, in my opinion. Compared to the Toyota Yaris I used to have, it's much less maneuverable.



          If the car was longer, say 5.0 meters long (like Tesla Model X), you couldn't maneuver the car through very tight corners. One of the reasons why I don't have a Tesla Model X (another being its width, third being its price).



          Now, Tesla Model X doesn't have a vertical rear window, the window being more like 45 degrees. My Toyota RAV4 hybrid has a vertical rear window.



          This means that if you want to transport large objects, a Tesla Model X with its 5.0 meter length is probably approximately as useful as my 4.6 meters long Toyota RAV4 hybrid. Same indoor dimensions at the roof level, much different external dimensions.



          Now, would a 45 degree rear window be better? I would say not better, because it would make the car too long externally if it has any useful large object carrying capacity, or make the car's carrying capacity too limited if the external dimensions are sensible.



          Am I alone in this opinion? You know, some people actually buy Tesla Model X. I even know somebody who has a Tesla Model X! Personally, I'm happy with my vertical rear window and wouldn't change to a 45 degree window. I'll buy an electric or plug-in-hybrid SUV the day when you can purchase one that has small enough external dimensions, large enough internal dimensions (necessitating a vertical rear window), sensible enough price and made by a reputable manufacturer I can trust.






          share|improve this answer













          The reason for the question in the title (why vertical?) is that car has a maximum possible length if you want it to be maneuverable in tight spaces. For example, my Toyota RAV4 hybrid is approximately 4.6 meters long. Quite long, in my opinion. Compared to the Toyota Yaris I used to have, it's much less maneuverable.



          If the car was longer, say 5.0 meters long (like Tesla Model X), you couldn't maneuver the car through very tight corners. One of the reasons why I don't have a Tesla Model X (another being its width, third being its price).



          Now, Tesla Model X doesn't have a vertical rear window, the window being more like 45 degrees. My Toyota RAV4 hybrid has a vertical rear window.



          This means that if you want to transport large objects, a Tesla Model X with its 5.0 meter length is probably approximately as useful as my 4.6 meters long Toyota RAV4 hybrid. Same indoor dimensions at the roof level, much different external dimensions.



          Now, would a 45 degree rear window be better? I would say not better, because it would make the car too long externally if it has any useful large object carrying capacity, or make the car's carrying capacity too limited if the external dimensions are sensible.



          Am I alone in this opinion? You know, some people actually buy Tesla Model X. I even know somebody who has a Tesla Model X! Personally, I'm happy with my vertical rear window and wouldn't change to a 45 degree window. I'll buy an electric or plug-in-hybrid SUV the day when you can purchase one that has small enough external dimensions, large enough internal dimensions (necessitating a vertical rear window), sensible enough price and made by a reputable manufacturer I can trust.







          share|improve this answer












          share|improve this answer



          share|improve this answer










          answered 3 hours ago









          juhistjuhist

          8,90163269




          8,90163269























              0














              There are basically two options to reduce air resistance at the rear of the car to a minimum.



              One is to make the rear flat and vertical. That way, the air flowing over the car doesn't create any turbulence until it has "passed" the rear of the car.



              The other way is to make body into an airfoil shape by bringing the roof level down smoothly and raising the floor level at the rear, so the air flow does not separate from the car bodywork. That has been carried to its logical conclusion in experimental solar powered cars (image source: Wikipedia)



              enter image description here



              Introducing a "backward facing step" by having a flat roof, a vertical rear window, and a flat top to the trunk is pretty much the worst of all worlds, aerodynamically. Hence the rear window is sloped to get closer to an airfoil shape.



              In practice, body designs are a compromise between aerodynamic efficiency, functionality and aesthetics - for example a 30-ton truck with a flat rear panel is both functional (to maximize the volume of the cargo space) and aerodynamic, but not pretty!






              share|improve this answer




























                0














                There are basically two options to reduce air resistance at the rear of the car to a minimum.



                One is to make the rear flat and vertical. That way, the air flowing over the car doesn't create any turbulence until it has "passed" the rear of the car.



                The other way is to make body into an airfoil shape by bringing the roof level down smoothly and raising the floor level at the rear, so the air flow does not separate from the car bodywork. That has been carried to its logical conclusion in experimental solar powered cars (image source: Wikipedia)



                enter image description here



                Introducing a "backward facing step" by having a flat roof, a vertical rear window, and a flat top to the trunk is pretty much the worst of all worlds, aerodynamically. Hence the rear window is sloped to get closer to an airfoil shape.



                In practice, body designs are a compromise between aerodynamic efficiency, functionality and aesthetics - for example a 30-ton truck with a flat rear panel is both functional (to maximize the volume of the cargo space) and aerodynamic, but not pretty!






                share|improve this answer


























                  0












                  0








                  0







                  There are basically two options to reduce air resistance at the rear of the car to a minimum.



                  One is to make the rear flat and vertical. That way, the air flowing over the car doesn't create any turbulence until it has "passed" the rear of the car.



                  The other way is to make body into an airfoil shape by bringing the roof level down smoothly and raising the floor level at the rear, so the air flow does not separate from the car bodywork. That has been carried to its logical conclusion in experimental solar powered cars (image source: Wikipedia)



                  enter image description here



                  Introducing a "backward facing step" by having a flat roof, a vertical rear window, and a flat top to the trunk is pretty much the worst of all worlds, aerodynamically. Hence the rear window is sloped to get closer to an airfoil shape.



                  In practice, body designs are a compromise between aerodynamic efficiency, functionality and aesthetics - for example a 30-ton truck with a flat rear panel is both functional (to maximize the volume of the cargo space) and aerodynamic, but not pretty!






                  share|improve this answer













                  There are basically two options to reduce air resistance at the rear of the car to a minimum.



                  One is to make the rear flat and vertical. That way, the air flowing over the car doesn't create any turbulence until it has "passed" the rear of the car.



                  The other way is to make body into an airfoil shape by bringing the roof level down smoothly and raising the floor level at the rear, so the air flow does not separate from the car bodywork. That has been carried to its logical conclusion in experimental solar powered cars (image source: Wikipedia)



                  enter image description here



                  Introducing a "backward facing step" by having a flat roof, a vertical rear window, and a flat top to the trunk is pretty much the worst of all worlds, aerodynamically. Hence the rear window is sloped to get closer to an airfoil shape.



                  In practice, body designs are a compromise between aerodynamic efficiency, functionality and aesthetics - for example a 30-ton truck with a flat rear panel is both functional (to maximize the volume of the cargo space) and aerodynamic, but not pretty!







                  share|improve this answer












                  share|improve this answer



                  share|improve this answer










                  answered 1 hour ago









                  alephzeroalephzero

                  1,0641510




                  1,0641510






























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