Drag coefficient 0.13 back in 1938
 

In Hucho's very good book on car aerodynamics (unfortunately in German, let me know if I should translate any terms for you) he describes a car designed in 1938 called the Schlör-Wagen (or "Göttingen Egg") that had an amazing drag coefficient of 0.13 !
Aerodynamik des Automobils ... - Google Book Search
If you browse through the book you'll find a number of aero gems.

Dr. Schlor's car was also mentioned in some of the postings below:

http://ecomodder.com/forum/showthrea...-car-1840.html

http://ecomodder.com/forum/showthrea...1930s-325.html

http://ecomodder.com/forum/showthrea...drag-1783.html

Hucho's book has come up a number of times on these forums, but I never thought to try Google Book Search. Thank you so much for providing the link! :thumbup:

It's available in English.

Thanks, Frank. I knew that, but haven't found the $100+ need to buy the English version. (Or are you referring to some on line English version? If so, please provide a link.) The link that Bearleener provide gives you access to pretty much the whole book on line - if you're willing to wade through it in German. (Wish I remember more of my high school German.) Just looking at the pictures is informative.