Running the heat can be energy draining because you don't have a hot engine to draw air from. Using the heated seats is much more efficient but of course less comfortable in cold weather.
I think running away as a child can be a very different situation than you imagine. "Running away" to the local park or your friend's house after a disagreement with your parents, sure. But a lot of kids run away because their basic needs aren't being met or they are being abused. Kids shouldn't be expected to be able to weigh the consequences of leaving a home with resources to avoid abuse, but adults should absolutely be expected to weigh the consequences of leaving society.
Running the heat can be energy draining because you don't have a hot engine to draw air from. Using the heated seats is much more efficient but of course less comfortable in cold weather.