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What kind of car do you have, how old is it, and how many miles do you have? What kind of engine?
Sounds like something you would hear on Car Talk!! Don't want to get in the middle of an argument...but...
Generally, on "modern" cars, you don't need to let them warm up. Modern fuel injection uses knock sensors to regulate the fuel/air mixture, bringing it up as close to "predetonation" and then backing it off again. On older cars, without this kind of control, you would get knocking or poor combustion due to the "cold" engine, until it got up to "operating temperature".
Now, if you live where the temperatures get below zero, if you don't use synthetic oil, it can take some time for it to get flowing well, and lubricating all the bearings- in that case I would recommend letting it warm up for a few minutes (you would want the heater warm anyway before you took off with those thick mittens) I had a cheap car (VW Fox), and I still put synthetic in it- it was nice to have it spin over fast on the first try, while all up and down the street was the "rrrrrr-rrrr-rrrr" of cars barely turning over in the cold!