Calculating Drag Coefficient from top speed?

[aerohead]

Originally Posted by JQmile

I found this on the web, and we all know the internet wouldn't lie to us

Looks like I was a little off, probably because I didn't factor in any rolling resistance.

"Among commercially available 1984 model street cars, the most aerodynamically efficient was the Audi 5000S, with a Cd of 0.33. The Chevrolet Corvette was close behind with a Cd of 0.34. Most other street models have approximate values of 0.40 (my wife's Chevrolet Chevette, I have discovered, is at the high end of the spectrum with 0.45)."

Mine's an '82, but you get the gist of its aero properties. They're bad. Nosecone maybe??

JQ,don't know if you're still out there but I scrounged up some old numbers on the Chevette.These are for the 1982 Euro version:
Cd 0.51
Frontal area 18.6 square-feet
Curb Weight 2,050 pounds
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Car and Driver did a road test comparison between a gasoline Chevette and Diesel Rabbit.Here are numbers for Chevy:
30-mph= 40 mpg
40-mph= 37.5 mpg
50-mph= 33 mpg
60-mph= 28 mpg
70-mph= 22 mpg
80-mph= 17.5 mpg
-------------------------------------------------------------------------- None of the road tests included top speed.Chevy's competitor,the 1982 Ford Escort was tested flat out at 87 mph.
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The OPEL Junior concept car of the 1980s would be a good car to mimic with the Chevette.It achieved Cd 0.30 with a remarkably short overall car length.