[aerohead]

MOTOR TREND hot-lapped the 2012 Porsche 911 Carrera S, at Laguna Seca Raceway, Monterey, California, USA. They use a trio of V-box, GPS dataloggers, accurate to 1/1000-th of a second for their quanta.
The following are data presented, and my dirty math:
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* Lap time 1: 39.30, ( 1.655-minutes )
* 36.2537-laps / hour equivalent
* @ 2.238-miles / lap = 81.1357-miles per hour average velocity
* 131.194-mph estimated maximum track velocity, between Turn-11, and Turn-1 ( from relationship to other Carreras also tested there )
* 'Blower-assisted' cooling drag associated with fan losses, motor losses, alternator losses, seven-pulley serpentine belt-drive losses, and engine losses = 4.307-horsepower at the fuel tank
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* Plugging 4.307-horsepower into the drag power formula at 131.194-mph, and solving for CdA, yields a 'blower-assisted' cooling drag - equivalency of CdA 0.2794 square feet during track mode.
* Adding to the CdA of the low drag Carrera yields CdA-e 6.1263-square-feet.
* Dividing by Porsche's Af = 20.8819-square-feet = Cd 0.2933
* Cd 0.2933 - Cd 0.28 = Cd 0.01338
* Cd 0.01338 + Cd 0.003 ( original 'high' Cd cooling system ) = Cd cooling-e 0.01638 ( 5.85% of total drag ) vs 1.07% total drag reported by Dr. Thomas Wolf.
* A 546% increase
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* Along with the Cd 0.002- 0.003 cooling drag mentioned for the MY 1997 Carrera, which became the template for later generation Carreras, Dr. Wolf DOES mention the ' blower-assisted' drag, however, it is not accounted for in the wind tunnel data.
* It requires a 'look' at the fuel tank in order to 'see' this additional drag, which has been exported away from the cooling system.
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* Like I said, this is just dirty math, back of the envelope stuff, however, this type of consumption must be accounted for on the Carrera's energy ledger sheet.
* Until this car came up in discussion, I was unaware that, any passenger car would rely on artificial airflow when at 40- mph ( 64.4 km/h ) or above. Typically, the dynamic pressure alone is sufficient for cooling.