From our weekly email:
This week’s green tip: Waiting in line in your car? Shut off your engine if you are in a drive-through. Running your engine while standing still gives you a effective mpg of 0, and exposes you to more toxic exhaust gases then if you were moving.
Let’s break this down. Fuel Efficiency, or your mpg, is computed by measuring how many miles you have traveled on one gallon of gas. If you are standing still while burning that gas, you are getting zero miles to the gallon. If you are stopped for more than 30 seconds, you use more gas idling than turning the car off and back on.¹ Besides costing you money and creating unneccesary pollutants, it can also be hazardous to your health.
CTA found that exposure to most auto pollutants, including volatile organic compounds (VOCs) and carbon monoxide (CO), is much higher inside vehicles than at the road side. VOCs and CO are linked to serious health problems–like respiratory infections and cancer–are known to shorten life. The highest exposure occurs when sitting in traffic congestion on highways or in a line-up of idling vehicles at a school or drive-through. From: http://www.hcdoes.org/airquality/Anti-Idling/idle.htm
Granted, reducing your exposure to exhaust gases by turning of your engine is much more effective if you are the only person in line. Even so, your car is still contributing to that cloud hanging around the McDonald’s drive through and it can only help you (and the environment) if you switch off the car.