What is the drag coefficient of a Cobra roadster?

[DMXF]

I have fairly extensive data which supports the premise that a Cobra roadster in "aero" race trim (tonnau, race windscreen, lowered, open side exhaust, etc) will do 200mph with 600 flywheel HP. The Cd shown in my analysis is somewhere around .61, although I don't know how accurate that is because I was using correlation factors to match the actual data.

My opinion, for what it's worth here but based in large part on real data, is that Dick Smith probably did 198mph. It's doubtful he had 600hp (which he said he did), given the single four barrel MR he was running and what was state of the art in '66. It's more likely he was around 530-540 (if he had a HR that would have added roughly 20hp), but that alone could have got him approaching 190mph and the other 8mph or so was likely due to the draft of cars in front of him and maybe some tailwind.