In a sense that is true, the amp draw will warm the battery. However draw is draw so I much prefer to put those amps right to the starting circuit. My 1991 Legacy was last driven sunday night, but I don't recall how cold it got. Last night, we hit -25 and at 2 PM today we were at -5 still. Looking at -25 again toinight. I've only had this car a short while, and I really dislike starting a motor for no reason. But I might fire her up tomorrow, early, just to see what she does. Not sure about how old the batter is, and it's too cold to check at the moment!
It was SO cold here today, I saw a Lawyer walking down the street with his hands in his OWN pockets!