Originally Posted by swamp2
Colder the better and higher density typically goes along with colder temperatures. Of course the cold starts are not good on an engine (nor batteries, belts, and a slew of other car things) at all but if the question is purely about power then colder the better. Growing up in Alaska the coldest parts of the winter (-40 to -50 deg F) made for some serious bumps in power.
Does density coincide with what normally is humidity? For example when Florida is 45 degrees will it be denser than when Nebraska is 45 degrees?