Leave the car running, turn off the headlights. Just don't do that when parked in a closed garage. I do that all the time in extreme hot or cold temps to keep the AC or heater running while at the grocery store. You can lock the car so the car doesn't get stolen, but in my neighborhood, there are plenty of vehicles left running with the doors unlocked, so that big souped up 4 wheel drive would be a better target than my volt
How in the world do you get a 56GB family plan? That must cost a small fortune per month