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Old 03-29-2021, 10:07 AM   #1 (permalink)
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Mercedes says 0.20 Cd for EQS electric sedan is record best for a production car




(EQS concept and camo production cars.)

UPDATE: scroll down a few posts for undisguised photos of the production car.

Quote:
Mercedes has claimed the throne of drag coefficient saying the EQS is the most aerodynamically efficient series production car in history with an astonishing 0.20 Cd.
Probably the most novel detail is the hood is a clamshell design to avoid cut lines on top of the fenders.

I wouldn't expect that's a significant aero benefit unless the car has laminar flow across the hood/fender transition, which would be unusual for a road car, no?

Relevant aero detail or harmless styling exercise?

Quote:
There are small inlets to cool the batteries, motors, and charger, but these have aggressive shutters to keep them closed when not needed for maximum aero. There is no hood shut line to be seen from the top, as it incorporates the tops of the front fenders, much in the same way Porsche’s Macan does. The car’s underfloor is completely smooth from front to back.
The article also describes alloy wheels with inserts between the spokes. But we've been seeing this on multiple EVs - eg. Tesla does this.


More pics at: https://www.autoweek.com/news/a35960...-aerodynamics/

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Old 03-29-2021, 05:37 PM   #2 (permalink)
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Yes, really interesting car. But the article is a bit breathless - traditional 3 box shapes have been on the wane for, what, decades?

No I don't think that it will have laminar boundary layer anywhere - just a few bugs would destroy that.

To my eyes the EQS just looks to be doing all the normal low drag things - full undertray, attached flow to back of car, clean separation edges at rear (hard to judge though because of camouflage), what appears to be a fairly aggressive rear diffuser angle.

Hope, hope, hope they release a tech paper though - front and rear lift figures would also be very interesting.
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Old 03-29-2021, 08:53 PM   #3 (permalink)
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Quote:
Originally Posted by JulianEdgar View Post
clean separation edges at rear (hard to judge though because of camouflage)

Unlike the concept vehicle, it's got the usual horizontal hard edge at the rear of the deck lid, but no vertical separation edges on the rear corners as sometimes seen on other low drag cars.

Here's a decent rear view even with the camo wrap:

https://cdn.motor1.com/images/mgl/LZ...rburgring.webp

Part of this set: https://insideevs.com/photo/5191843/...s-nurburgring/
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Old 03-31-2021, 11:42 AM   #4 (permalink)
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8- counts lower than Tesla

So the EQS is 8-counts lower than the 2021 Model S Plaid. Easy to best in the next 'refresh' or slam, if a body-in-white redo of the long-in-the-tooth Model S.
I'm always happy to see lower drag.
Hope they can catch up to the 1993 EV1 LSR some day. Or the 1997 M-B F300.
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Old 04-16-2021, 10:14 AM   #5 (permalink)
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undisguised car - more details

The company revealed the undisguised production version yesterday:



Notable: that deck lid spoiler is somewhat unusually narrow.



The feature behind the rear wheel might be a pressure vent from the wheel well that aids separation at the back corner. We've seen that on a few production cars. Or it might just be there to trip flow from wrapping at the rear (or both).

And of course the door handles are flush, which is seemingly now a required EV party trick - arguably popularized by Tesla.



If you zoom in on this image, it looks like the outside of the side "vents" have a passage, possibly for a front wheel "air curtain".

And while the front upper "grille" is smooth, the lower grille surprisingly does not appear to have shutters - doesn't that look like a heat exchanger visible in there?



Mercedes’ press release about the car is 62 pages long!

Relevant aero subsection: (aha - it mentions grille shutters...)

Quote:
The new EQS: Aerodynamics

Less resistance for increased range and quiet: With a cd value from 0.20,1 it sets a new aerodynamic benchmark for production vehicles, resulting in improvements for the range. It is also among the best in terms of quiet running. A great deal of attention to detail lies behind the aerodynamic and aeroacoustic performance.

The purpose design with smooth underbody and mostly closed radiator shutter as well as the favorable basic shape were a solid starting point for the flow optimization. With a great deal of meticulousness, the aerodynamicists in close cooperation with designers were able to achieve the new record cd value of 0.20.

The frontal area of the EQS is 2.51 m2. This results in an effective air resistance from 0.5 m².

The spread of the individual variants in terms of cd value is comparatively small - customers thus have a wide choice of models without having to consider the range. Mercedes also offers aero wheel options, which were optimized in the wind tunnel, in 20 and 21 inches.

Behind the aerodynamic performance required a lot of attention to detail. The EQS is the first representative of the new electric platform. This is why the invisible details, such as those on the underbody, were developed diligently with great attention to the smallest details. Several thousand computational runs were performed in the virtual wind tunnel alone. Below are some details of the aero development:
  • Aerodynamically favorable dimensional concept and tires with optimized geometry
  • Aerodynamically optimized wheels in the dimensions 20 and 21 inches
  • Cooling air control system with innovative transverse lamella makes extremely efficient use of the available installation space
  • Continuous seals in the front area, i.e. between service flap, Black Panel and headlamps
  • Streamlined design of the A-pillar
  • Wheel spoilers at front and rear. The rear, arrow-shaped wheel spoiler was developed by a fluid dynamics expert directly in the wind tunnel for the benefit of a greater range.
  • Elaborately matched underbody paneling in the rear-axle area to take even greater advantage of the smooth underbody of the battery.
  • The rear spoiler benefits both rear-axle lift and aerodynamic drag.
For more than three decades, the aerodynamicists at Mercedes-Benz have been achieving top results. Currently, the A-Class Sedan (V 177) and the S-Class (V 223) are the worldwide record holders with a cd value of 0.22.

The special simulation tools and the Mercedes-Benz aero-acoustics wind tunnel commissioned in 2013 make a decisive contribution to this. The EQS also received its fine-tuning there.

Extensive sealing and insulation measures reduce wind noise


In an electric car without the usual level of powertrain sound, wind noise is particularly noticeable by the occupants. That is why the aeroacoustic behavior is particularly important.

In this area, the new EQS is one of the very best vehicles in its class.


Special attention was paid to the sealing of the transitions between the six side windows.

The seals on the flush-fitting door handles, the window support and on the raised exterior mirrors are also noise-optimized.

A further contribution was made by the newly developed A-pillar with a specially shaped piece of trim at the transition to the windscreen. The development is supported by both modern flow simulations and external noise measurements using a special microphone array in the wind tunnel. The A-pillar is designed in this way not only to improve the aero-acoustics, but it is also important for a low cd value and to keep the windows free of dirt.
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Old 04-16-2021, 10:46 AM   #6 (permalink)
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What helps to get lower drag figures is ofcourse the air suspension. At the moment they haven`t told the at which ride heigth the 0,20 is achieved.

Also the turning rear wheels help little as front wheels don`t have to turn so much. More flat panels can be onderside of the car.

Havent seen any pictures yet on the underside of the car, because most magic is there.
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Old 04-16-2021, 10:51 AM   #7 (permalink)
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Yes, there are a few asterisks on the specific options / settings required to reach 0.20



- Specific wheel/tire combination (possibly not the ones shown in the photos)


- The ride height issue is hinted at in the press release where a specific "drive mode" must be selected for the lowest Cd.
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Old 04-16-2021, 11:06 AM   #8 (permalink)
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It is quite interesing to see a relatively "normal" shaped car reaching such a low CD.
After aerodynamic desasters such as the BMW i3 and Nissan Leaf (both 0.29) or Mitsubishi I-Miev (0.35) it's nice to see EVs getting shaped more aerodynamicly, like the EV-1 (0.19).
After all, aerodynamic drag is THE factor for highway range.
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Old 04-16-2021, 11:14 AM   #9 (permalink)
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Sadly, the sedan is a dying vehicle format.

As you point out, we're unlikely to see 0.20 for a SUV/crossover body style.

Unfortunately, that's the style of vehicle people overwhelmingly seem to want to buy and what marketing departments are pushing people to want to buy.
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Old 04-16-2021, 11:25 AM   #10 (permalink)
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I meant "normal shaped" as in not basjoos civic (0,17) or a Milan SL (0,076), but yea SUVs are just terrible.
They are like offroad vehicles on the road and like road vehicles off road while offering less space on the inside than wagons.
Many even offer less space for tall drivers than the original Smart ForTwo.
Plus they have terrible visibility, often ridiculously high weight and to load something into them, you need to lift it rather high first.

What are they even good for?

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