Why is S car fuel mileage so poor?

[Enzeder]

At 11:28 AM 9/26/2004, Brett Dikeman wrote:
>A 340hp V8, accelerating a 4,000lb car to 50mph- is going to use a bit 
>more fuel than a 300hp V8, and if it does so faster, the car will spend 
>more time at a higher speed.  Lower gearing makes a difference too, it 
>takes a little more energy to throw everything around faster, etc.  Over a 
>10 mile test, these things all make a difference.  I know if I accelerated 
>very lightly and drove 10mi, I'd get a drastically different average 
>mileage result than if I accelerated hard and drove 10mi.  Probably close 
>to several mpg...

To see if this happened with other vehicles, I looked at the 'Vette - Z06 
vs base (another car I could think of that had the same body and engine 
type, but different outputs).  Both 'Vette's have almost identical mileage 
ratings (if you believe the posted numbers - from say: 
http://www.new-cars.com/2002/chevrolet/chevrolet-corvette-specifications.html). 


I'm not saying I didn't expect losses for the S cars, just not in  the 15% 
range.