There are two major sources of CdA numbers that I've been using. Neither is ideal from the point of view of authentication. They are:
http://www.mayfco.com/tbls.htm
http://en.wikipedia.org/wiki/Automob...g_coefficients
The problem is that I believe a lot of the wiki info came from the mayfield (mayfco) numbers, so they're not an independent confirmation. Second, many of the mayfco numbers are estimates, but they don't say which ones, nor do they say which part (Cd, A) is estimated.
In addition to the above, I have occasionally found, for newer cars, CdA numbers from Car and Driver (their full reviews often have them), manufacturer websites occasionally have Cd numbers and you have to estimate the area (I am finding that .85 of WxH seems to give a decent number). I haven't been looking at newer cars much because for my application they weigh too darn much. Seems like for every year after 1995, the same exact car model puts on about 200 lbs.
Do you know of other sources for this info?
--Steve