Leonidas, you are incorrect.

I recounted this story yesterday - I flew home with my family to Newark airport two nights ago and took my son (he’s 7) with me to get our car. As it was about 25 degrees outside, I let the car warm up for a few minutes - and my son asked me if I was wasting gas. I explained to him that the car runs more efficiently, and will last longer, if it is allowed to warm up properly in cold weather.

No, that is what you DO NOT want to do to help your engine. That is more of an urban legend now, nobody recommends a car to idle in the cold for several minutes to warm up. You are better off to just start driving it after it starts, the oil heats up faster that way, and you end up with less time that the engine is running with cold oil, and a cold engine idling for several minutes does waste gas, again it will warm up faster if you just start driving it.

Your son is correct. Be proud :)