The way I was raised, you get dressed for the elements before going outside. If my car gets warm I turn the heat off.Do you guys keep a hat and gloves in your car? Blanket? Spare jacket or sweater?
Getting to the car from garage, or vice versa, rarely seems to be the issue. What happens when you break down or get stranded when it's cold?
If everyone really just wears a sweater or t-shirt you're not going to have a good time.