Winter time car seat question.

So I’m wondering what parents would do it this situation. I know you’re not supposed to leave your babies in the car while you’re not in it. But what about when you go in to pay for gas? I’ve always brought my daughter in but recently she transitioned to a convertible car seat and we have heavy winters. There’s not pay at the pump option in our small town. Would you bring her in or leave her in the car?