[NeilBlanchard]

Originally Posted by RobertSmalls

Here's the drag coefficient calculation for y'all to play with:
(7200W*.85-(3400lbs*9.81m/s^2*.008*60mph))/(.5*1.225kg/m^3*(6 0mph)^3)/17.3ft - Wolfram|Alpha

Now here's the problem, as Orange4boy correctly points out. This very aero car expends about half its energy overcoming rolling resistance at 60mph. If the Crr is only known to within 20%, the Cd can not be known in any meaningful way.

For Crr=.006, Cd=.194
For Crr=.008, Cd=.151
For Crr=.010, Cd=.109

One of the details that I forget if I have already mentioned: Dave said that he was/is using lousy old tires that he just had laying around -- they are somewhat out of round, and not particularly true, either. So, I'm leaning towards the Cd = 0.109 end of the range!