In such a situation, it is generally considered polite to say "thank you" when someone holds the door for you. Saying "thank you" is a simple and courteous way to acknowledge the person's gesture and show appreciation for their kindness. Even though holding the door for someone is a small action, expressing gratitude is a way to promote positive interactions and create a friendly atmosphere in public spaces. So, if someone holds the door for you while you are dressed in public after gasing up your car, it's a good idea to say "thank you."