I wouldn't say the Civic and Focus are similar at all, aside from the fact that they're both hatchbacks. 3 major differences that stand out: the Civic has
significantly more rear taper in plan & profile than the Focus, and its height is less than the Focus as well. The Civic's roofline also extends much further to the rear of the vehicle than the Focus.
If you're going to be skeptical of all published Cd figures, then your only solution is to do it yourself. Since you don't have a wind tunnel, you can figure it out via coast-down testing:
http://www.instructables.com/id/Meas...t-of-your-car/