Saving energy
Don't go in the drive through if you are at a restaurant.
What do we waste?
If you go through the drive through, you could pollute the air because your car is still running and you could also waste your car fuel.
Would you wouldn't be doing
If you go through the drive through you would not be reducing your carbon footprint. And you also would not get any exercise.
What you could do
You could park your car in the parking lot and go inside and order your food. This way you can not pollute the air and you could get some exercise. You also won't waste any car fuel.