New world's best Cd for a current production car: 0.24, Mercedes 2009 E-Class coupe

[cfg83]

lunarhighway -

Thanx! I wanted to know what was going on under there. It's grooved in the back. Would that be for structural integrity or aero or both or a compromise?!?!?!?

CarloSW2

[Wilden]

Looks very interesting, good find with those pictures.

[Cd]

I wonder if the Cd figures that are published are accurate with the stock wheels.

It seems as though there would be a lot of turbulence within the wheels.

The Lexus LS460 also has huge open spoked wheels as well, yet has a .25 Cd.

I remember reading that some of GMs' Cd figures were given with the rear view mirrorS removed, and other tricks to bring the Cd down.

[MetroMPG]

I think lunarhighway is right: the most efficient variant of this coupe will have different aero features than the performance version. Including the wheels, I'd guess.

[aerohead]

Originally Posted by Cd

I wonder if the Cd figures that are published are accurate with the stock wheels.

It seems as though there would be a lot of turbulence within the wheels.

The Lexus LS460 also has huge open spoked wheels as well, yet has a .25 Cd.

I remember reading that some of GMs' Cd figures were given with the rear view mirror removed, and other tricks to bring the Cd down.

I'm not sure about other countries,but in the U.S.,the sideview mirrors are not factored into the frontal area reported by automakers to the EPA.So the Cd is skewed a little higher to compensate for the absence of the frontal area of the mirrors which are present during windtunnel drag measurements.Silly!

[CobraBall]

Originally Posted by Daox

Impressive. Now scale the car down so it weighs around 2000 lbs and throw a ~1.0L diesel in it and let me drive to my heart's content.

Benz could get the weight down to 2000 pounds BUT...

The cost would be doubled or tripled or quad... (however its spelled). $$$$

The aluminum frame, ah la Vette or Ferrari 360 Modena. $$

Totally Carbon Fiber body, interior and exterior, CF seats. CF-Very Expensive. No robotic CB construction-hand built. $$$$

Carbon Fiber Ceramic disk brakes, titanium differential & transmission case, CB drive shaft.$$$

Titanium diesel engine. $$$$$$$$$$$$$$$$$$$$$$$$$$

Inquiring minds want to know "how large would the carbon footprint be for a carbon fiber car?"

[donee]

Hi CobraBall,

Check out Fiberforge: Lightweighting Your World With Thermoplastic Advanced Composite Parts . With this process, cars built from Carbon Fiber reinforced plastic are actually cheaper than stamped steel up to a 10's of thousand per year.

[Frank Lee]

"Benz could get the weight down to 2000 pounds BUT..."

I think they could put it on a diet... maybe not to 2000 lbs... but significant if only they'd throw all that c rap out that doesn't make it go that it's burdened with.

[lunarhighway]

did some more digging

on the official belgian mercedes site the normal sedan version of the new E class is already listed, and torough as always mercedes has a very comprehensive pdf with technical data for the car, which actucally lists the Cd vanues for various variants.... these range from 0.25 for the
E 200 CDI BlueEFFICIENCY to 0.28
by no means bad! and it totally explains why the coupé is able to get 0.24 ... the different roofline alone could nock of this extra 0.01Cd off on the other hand a fitting wider tires will quickly ruin a lot of slipperyness.... the blue efficientcy is mercedeses "eco tweaked" badge... most car manifacturers in europe have introduced some blue, or eco whatever variant... these have cleaner emissions and often tweaked aero, such as underbody pannels and lower ride height... also on some brands certain un-ecofriendly options are absent.

interestingly the pdf also contains a scale drawing with a topview. the site itself also has a nice 360 view with a very nice zoom... to bad it's not truely 3d as i'd move the camara underneath, but you can get a pretty good look at the wheel dams... i assume the front of the cars are identical

here's a direct link the the pdf wich is in german apparently.... i'm sure that when the coupé comes out they'll post something similar.

hope this works and don't sound any bandwithalarms in stuttgart:

http://www.mercedes-benz.be/content/...ta_02-2009.pdf

[lunarhighway]

The coupé just appeared on the belgian mercedes site.... BUT

the sleekest version listed only has a Cd of 0.26... and most versions have 0.27

pretty good in the real world but a bit disapointing.... likely the coupé doesn't come with certain trim options wich would give a little lower drag maybe

so 0.24 certainly seems possible in a slightly lowered version with a smaller engine that allows the actuall grill to be reduced a bit furher and skinny tires.

to soften the blow, here a topview drawing...