Having said all that, when I tested cold (~55 F) vs. warm (~116 F) intake air @ 39 F ambient with my car, it made no significant difference. No gains or losses:
Details:
http://metrompg.com/posts/wai-test.htm
Not saying this will be the case for every vehicle. Also, my testing of this mod wasn't ideal (no additional set of "A" data).
As with much in life, "it depends."