[trebuchet03]

Originally Posted by DieselHybrid

"the C-Class merc takes in fast moving air under the car, and ejects it out of slits in the tail light lenses."

Can you provide a link to this information, because I find it highly unlikely.

Sure
New C-Class: Ventilated tail lights - worldcarfans

Here's another source
eMercedesBenz - The Unofficial Mercedes-Benz Weblog

OFFICIAL PRESS RELEASE


New C-Class: Ventilated tail lights for better aerodynamics

Stuttgart, Feb 07, 2007
Two Mercedes patents that bring significant aerodynamic advantages are being used in the new C-Class for the very first time. Mercedes engineers have invented innovative "ventilated tail lights" which replace conventional spoiler lips....


The first technology, ventilated tail lights, have been implemented to replace conventional spoiler lips and help direct air flow along the side of the vehicle. The lights, which are hermetically sealed against the vehicle, function by taking air sucked from the underbody and forcing it through ventilating slits. Without them, the slipstream would be conducted behind the rear of the vehicle at the tail lights, resulting in unfavorable turbulences which negatively impact air resistance, rear axle lift and yaw characteristics.

I can't post where I originally found it because of licensing... But I did find it originally in a tech journal

Originally Posted by DieselHybrid

First, this, in and of itself, would not reduce the drag coefficient to 0.27.

Seriously, did you not read the original post?

The C-Class has a cD of .27 - probably not all tail lights... but they did spend the R&D time and money and then more time and money to make it... One would be led to believe that they decided gains were to be had....

Originally Posted by DieselHybrid

The added ducting (if it exists) would actually increase vehicle drag.

Thus far, my cfd results show otherwise (depending on location, of course).... weather or not they are right is another story Can you provide some links/evidence for that claim?