I don't know about other cars, but here are the logged IAT's from my car on the same day with almost identical
ambient temps (taken about 1 hour apart @ ~68 degrees F., ambient).
Cone filter mounted on short alum pipe in engine compartment:
Same cone filter, mounted in fender:
Those were taken during 3rd gear freeway tests, not on a dyno. based on my experience with the car, i don't
think air circulation is very good in the engine compartment and have made my own mods to help get the air
in/out of the area. (these logs were taken before any air circulation mods)
-mike