That was my first thought - ambient temperature.
I suppose if you had a mega efficient intercooler, you might need it for inlet air temperature
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quattro RR - crystal silver
quattro WR - 1981 Lombard RAC rally recreation (50% share)
Nissan Navara - tow car / service vehicle for above
A4 2.0T quattro s-line special edition - wife's
http://www.flickr.com/photos/37654549@N06/sets/