Why is S car fuel mileage so poor?

[Enzeder]

Why would they make more power?  Remember, this is in a highway cruise test.


 From the EPA web site: "The highway is a 10 mile trip with an average 
speed of 48 mph. The vehicle is started "hot" and there is very little 
idling and no stops."




At 05:25 PM 9/25/2004, S Dewitt wrote:
>You have to make power somehow... More fuel + more air =  more hp..
>The S cars probably run a richer mixture to combat detonation...
>
>Scott DeWitt
>Advanced Automotion
>817-939-6761
>----- Original Message -----
>From: "Enzeder" <enzeder at comcast.net>
>
>
>Why are the S cars mileage numbers so low?  I figured consumption would be
>a matter of engine load and efficiency.  As both engines are pulling the
>same weight (and shape in the case of the S8), the load should be roughly
>similar.  So does that make the S cars 15% engines less efficient?
>
>Take the S8 for example.  Two naturally aspirated V8's of the same
>displacement and hauling the same weight.  Looking at highway numbers (as
>it's fairly steady state):
>S8 vs A8 (both 2001)
>21 vs 24 mpg
>4024 vs 4068 lbs
>360 vs 310 HP
>317 vs 302 ft/lbs
>11.0 vs 10.8 comp ratio
>13.9 vs 14.2 ¼ mile
>6.3 vs 6.7 0-60 mph
>An aside: 345x30mm vs 312x25mm (323x30mm for the A8L)
>
>
>As for the S6:
>S6 vs A6 4.2 (both 2002)
>21 vs 25 mpg
>4024 vs 4024 lbs (surprised by this)
>340 vs 300 HP
>310 vs 295 ft/lbs
>11.0 vs 11.0 comp ratio
>14.5 vs 15.0 ¼ mile (14.7 for the 2.7tt w/6-speed)
>6.5 vs 6.7 0-60 mph (6.0 for the 2.7tt w/6-speed)
>Curiously, both have 321x30mm front rotors.  I expected the S6's to be
>bigger.
>
>Numbers taken from the AudiWorld site.