Mercedes aero engineer: Cd of .20 feasible in production cars within 10 yrs
 

Found an interesting article about Dr. Teddy Woll, head of aerodynamics at Daimler. There's no date on the piece, but judging by the absense of discussion of the Cd 0.24 E Class coupe, I'm guessing it's older than this year.

He talks about the challenges and opportunities in making cars ever more aerodynamic, which is a stated goal of Daimler - see Mercedes to Sell Super-Aerodynamic Cars in 5 Years | Hypermiling, Fuel Economy, and EcoModding News - EcoModder.com .

Answers questions like:

Which components of cars do you believe have the greatest potential for aerodynamic improvement?

"The big action is at the rear," of course. (No news to EcoModders.) And he describes things the company is doing, and what it could potentially do. Plus chatter about wheels/wheel wells/underbody.

What do you think is the lowest drag coefficient possible for a mass production car?

Spoiler alert: Cd 0.20

He uses the GM Aero - Cd. 0.14 - as a starting point of an "impractical" aero car and lists several of its unacceptable aero features that would need to be compromised for reasons of safety/performance/practicality.

Not sure if he's referring to this car "GM Aero 2000"

http://us1.webpublications.com.au/st.../0565_10lo.jpg

Anyway, worth a read:

"A Drag Coefficient of 0.2 Represents the Sound Barrier" - ATZ online

...the date on the picture is "woll_090130.jpg" which seems to imply Jan 30 2009, so it could've been late 2008 or early 2009.

That is confusing- his comments about the GM "Aero".

The Aero X certainly looks garageable... has body seams... so it shouldn't be that.

The Aerotech- especially the longtail- is long enough not to be garageable... has no seams really... but it's obviously not a road car... has no back window either... has cooling openings...

http://i146.photobucket.com/albums/r...concept-ca.jpg

Maybe his memory has failed him and he's got these two cars combined in his mind? Or there's another GM aero car we don't know about? :confused:

A perfectly designed full boat-tail on my Tempo would get me from .36 to .306? I thought they were potentially worth more than that...

Old Tele man -

Good web detective work. I use that trick too from time to time.

CarloSW2

Lets see. I have a car that has no problem fitting in a garage, has no problem with excessive heat buildup inside from the angle of the windshield, no problem with brake cooling, has a cooling air system (is he talking about the engine radiator or the A/C?), and is practical enough for daily driving all year around. And its Cd is.....

...there's INSIDE-the-company mindsets and OUTSIDE-the-company mindsets.

...let me guess, Dr. Woll's was INSIDE "M-B" and not INSIDE "GM" for sure.

i recentyl came accross this article about the pinafarina aero car experiment with an 0.201 Cd it wouldn't look even half as unconventional today as it did back than.

Popular Science - Google Boeken

also it just seems to get the basics right, and without compromising practvality or intyroducing shapes that would be difficult to make.

if you start with the best possible shape and that make a few compromises to turn it into a car you'll always end up with something better than when you make a car and than compromise the styling to get it a bit aero

Oh, my! The banana car :)

I always thought the Ford Probe V was a good looking car, and only 25 years old!
http://www.carstyling.ru/resources/c..._01[1].jpg
http://www.carstyling.ru/resources/c..._02[1].jpg
http://www.carstyling.ru/resources/c...d_probe5_4.jpg
http://www.carstyling.ru/resources/c..._probe5_02.jpg

It had a .137 cd and doesn't look as if it would be too difficult to produce today.

What ever happened to that Benz Boxfish prototype?

if you look at the e class coupe and be boxfish here's more than just a few panel folds that look similar to me, so it's not because the boxfish itself isn't put in production some of the (less obvious) aero lessons learned from it aren't put on pruduction models.

...I kinda like the little "fin" on the trunk deck lid (rear looking camera or brake light?)!

Chevy Citation-IV
 

I think he's referring to Chevrolet's Citation-IV concept which was out at the same time as the Ford Probe-IV.But I think he's giving the Chevy the Ford Cd.
The Chevy was 0.15or .16 and Ford 0.14.Then Ford went on to do the Probe-V which came in at Cd 0.137.
I think the Chevy is in my photo archive on front page of CAR and DRIVER,who road tested both cars.I intended to do a "case-study" on both cars,haven't got around to it.
Where do the days go?

They go into fixing Microsoft's blunders. :mad:

http://ecomodder.com/forum/member-ae...per-cd0-15.jpg

I wondered if he was referring to this car as well (GM's Citation IV with generous teardrop taper. Cd0.15 - according to your gallery) - though it's also got seams, which the Daimler guy said it didn't.

Hi Darin,

Did you say that Aerohead has a gallery? Can someone post a link to it, please?

Yup: Fuel Economy, Hypermiling, EcoModding News and Forum - EcoModder.com - aerohead's Albums

Now THOSE are some wipers that'll wreck it all!

wrong again Phil!
 

I mis-spoke with respect to the Citation.It has Cd 0.18 not 0.16.

100 mpg Mercedes with Cd 0.18
 

I found my article about a Cd 0.18 Mercedes that achieved 100 mpg a decade or so ago.I'll photograph it and have Al transfer it onto the net Saturday.

now I'm completely confused!
 

I just read Mr. Voll's article,thanks Darin!
If he is referring to the GM Aero( which used to reside at the GM exhibit at Epcot Center,Orlando,Florida),it had a higher Cd than the Citation.
The Citation never had a bellypan,hence it's higher Cd than Probe.
As far as gaps,every real car has got to have "cut lines" for the hood,doors,trunklid,fuel door/charging port,etc..He may have been referring to a development model.I don't know.
GM's Program For New Generation Vehicle(PNGV) 80-mpg car,circa 2004 came in around Cd 0.165.
They started with the EV-1 in the windtunnel,and did two development teams in parallel to develop a body in white.
Their "solution" addressed many issues Mr. Voll cites as barriers to lower drag in production cars.
There's a good chance I've missed some things,as after Clinton left the White House it's been really difficult to look out the window.

I think I found the reference Really!
 

The October 1999 issue of MECHANICAL ENGINEERING has an article about the development of GM's 80-MPG Precept concept car.
During wind tunnel studies one of the 1/3-scale clay models came in at Cd 0.146.
In full-scale,and adding wipers,wheel covers,mirrors(cameras),door handles,and cut lines,the drag coefficient rose to Cd 0.163.
My guess,is that this is the Cd 0.14 model referred to.
Underfloor heat issues are solved by the rear engine layout ( yeah Preston Tucker,you're vindicated!) and the rear cooling solves the issue of the open nose.
I'll post a photo of the Precept when Al gets un-busy.
Also I have a pic of the Cd 0.18 Mercedes-Benz F300 research vehicle of 1997,which attained 100-MPG.

photo: Cd 0.18 M-B/ GM Cd 0.14
 

here are pics

Aerohead, you found it!! The 0.14 Cd GM is just what I was looking for in Chrysler diesel-electric hybrid.
Do know where I can find more info on it? Does it have a (code)name?

Precept
 

Piwoslaw,my photo comes from the June 2000 issue of POPULAR MECHANICS,on pages 88,89,and 90.On page 90 is a phantom view with cutaways.
You might be able to get a reprint of the article from the POP MECH.This article also touches on Ford's "Prodigy" and the Dodge ESX3.
These were to be the 80-mpg cars although there were never commitments made to production.
Let me know if you have trouble with the articles,we'll work somethin' out.

Hi,

I found some additional pictures of the GM Precept:

GM Unveils Concept Car That Gets 80 Miles A Gallon

http://www.electrifyingtimes.com/GMPrecept1.jpg
http://www.electrifyingtimes.com/GMPrecept3.jpg
http://www.electrifyingtimes.com/GMPrecept2.jpg
http://www.automobilrevue.de/images/Precept1.jpg

That web page quotes the Cd as 0.163. It has video mirrors. An electric motor drives the front wheels and a small diesel drives the rear (hence the cooling vents in the rear sides).

NeilBlanchard -

I get so depressed when I see these cars. Maybe not ready for prime-time, but still birds in the hand.

CarloSW2

Alfa Romeo BAT 5 in 1954 claimed cD of .19.

So I suppose it is pretty safe to go out on a limb and predict that in 10 years from now we will be able to achieve what we did 50 years ago.

So this is where the "Bigger, Better, Faster, More" philosophy got us: as time went by cars had bigger Cd, bigger frontal area, bigger fuel consumption, etc...
Only was it really better?

upshot
 

The upshot for me,is that whenever these cars emerge,they basically confirm assertions going back to at least 1922,when the Jaray/Klemperer work was published,which infers what WILL happen,should truly low drag vehicles make it onto the roads.
With fiberglass cloth and polyester resin I can mimic the successes of the Masters and taste the sweet fruit of their endeavors.
Cogito,ergo imodifi !

Are you sure about all of that? My '76 RamCharger was smaller than my '00 Ram. I have a smaller engine that produces more power (360 vs 440) and I get double the mileage (16 vs 8). I think the 'Better" part of your original saying applies to fuel mileage too.

Hell, the C5 Vette will easily get 30 MPG out cruising, not bad for a Sports Car!

What is the Cd of a Corvette? It's about a wedge of cheese... I'd think it'd be pretty good!

Jethro: You got me!
By no means did I give the full picture, where average FE has gone up since, say, the 1960's or '70's. In my post I was referring to the masses of people giving up econocars for SUV's and phat-@$$ pickup trucks. Plus the fact that today's "superslick" Cd's of circa 0.24-0.28 were something new back in the 1930's and '40's. Since then car companies have been reinventing the wheel every few years, repackaging it and advertising it as if it was a first.

Another thing about many "firsts" is that the "discoverer", upon having his epiphany, thinks this is the first time anyone thought of it. L O L ! Outside of electronics, much of what we think is "new" and "hi tech" today was discovered and reasonably refined 80-100 years ago.

Do you happen to have more info on this F-300? Every internet search I have done has turned up a 3-wheeled vehicle designed to tilt in turns(similar to a car called the "Carver"), with the two front wheels being exposed. This three-wheeler is often referred to as the Mercedes-Benz F300 LifeJet, and I know for a fact that this is not same the car you have referred to and posted pics of. Maybe the photo you posted has the wrong name?

I'm trying to gather specs on all of the hyper-efficient cars I can find. I want to know Cd, curb weight, engine type/displacement/horsepower, mpg, 0-60 mph acceleration, and top speed, mainly, along with any notable features the car has.

F-300
 

The Toecutter,sorry,I'm brain dead,and will have to dig the article back out.The photo of the 100-mpg M-B was small,with just a brief commentary.
I've seen no reference to it since,however I let all my subscriptions laps,and I have no idea what I've missed.

F300 and references
 

I found the F300 article.AUTOMOBILE MAGAZINE,March,1997,page 10.
The article was by Georg Kacher.
The photo credit is: KPG PHOTOGRAPHY / AUTO BILD.
You might hook up with the magazine online and get directed to Mr.Kacher,or if near a newstand,check for the magazine's address and send them slow mail,Attn: Georg Kacher.
A F200 concept was displayed at the Paris Auto Show.
The F300 is :5-passenger
' B-class'
1760-pounds
3-cyl with cylinder de-activation
high-pressure common rail EFI
Balance-shafts
TDI 1.8-liter
110-Bhp
CVT (transmission)
FWD
0-60 mph in under 10-secs
110 mph top speed
100-mpg
That's all I have.Good luck,and let us know if you locate additional info.

In the interceding 25~30 years, have any car companies claimed to beat teh Probe V's 0.137 Cd?

beat
 

To my knowledge,no auto maker has claimed a 'producible' automobile at lower than Cd 0.137.
The closed-course pulse-and-glide set have reached down below Cd 0.8 ( NUNA-3).Not sure the typical consumer is quite ready for that one.

M-B F300 larger photo
 

I found the original article and we scanned the photo into PhotoShop for a larger image.
A more conservative 'look' than the 2016 M-B slider-tail and 10-counts lower Cd
http://i1271.photobucket.com/albums/...ntitled-21.jpg

Thanks for resuscitating this thread. Here's a low drag Mercedes concept, with a Cd of 0.19:

http://roa.h-cdn.co/assets/15/38/980...1-1280x846.jpg

This is from Wikipedia, but it looks eerily familiar - the Bionic (aka Boxfish) car is also Cd 0.19:

https://upload.wikimedia.org/wikiped...comparison.jpghttp://images.thecarconnection.com/l...00009713_l.jpg