Idling FAQs

With modern emission technology and more fuel-efficient cars, why do I have to worry about a small matter like idling?

Automakers have succeeded in cleaning up most of the harmful substances emitted by vehicles. Compared with unregulated vehicles 30 years ago, today’s new cars generate 98 percent fewer hydrocarbons, 96 percent less carbon monoxide and 90 percent fewer nitrous oxides. However, vehicles still emit a great deal of air pollution, including carbon monoxide, nitrogen dioxide, particulate matter, volatile organic compounds and carbon dioxide. Vehicle exhaust also contributes to ozone formation.

Every gallon of fuel burned produces about 20 pounds of carbon dioxide. How can one gallon of gas produce so much air pollution?

Two factors contribute to the high output of carbon dioxide per gallon of fuel burned:
First, fuel burns in the presences of oxygen that it gets from the air. Since air is only one-fifth oxygen, large quantities of air are needed to burn gasoline.
Second, gasoline is rich in carbon which is converted to COwhen burned in the presence of oxygen. Because large quantities of air are required to burn gasoline, large amounts of CO2 are produced.

What other air pollutants are found in car exhaust?

Unfortunately, car exhaust contains three major air pollutants that are harmful to public health and the environment: carbon monoxide, nitrogen dioxide and particulate matter. Diesel engines tend to produce more particulate matter than regular gasoline vehicles.
Nitrogen dioxide contributes to the formation of ground-level ozone, a fourth major air pollutant that leads to smog.

How much fuel am I wasting by idling my vehicle?

The cost of idling your vehicle for 10 minutes every morning can add up. Idling for just ten minutes wastes about a fifth of a gallon of gas. It may not sound like much, but it all adds up. Think about how long do you idle each day, each week, each year? And remember, millions of motorists are idling.

What are the most common reasons for idling?

  • Warming up a vehicle.
  • Drive-thru windows, such as fast food, ATMs, library book returns and other quick errands.
  • Waiting on someone, especially picking up and dropping off children at school, athletics, library and other extracurricular activities.
  • Stopping to talk to an acquaintance or friend.
  • Preparing to leave the house, on lunch breaks, checking email and voicemail, talking on the phone.
  • Waiting to get gas, at the car wash or at active railroad crossings.
  • What steps can I take to minimize idling?

    It’s easy – think about fuel efficiency every time you use your car.
    1. Never leave the vehicle running while you zip into a corner store or fast-food restaurant – it’s hard on your wallet, bad for the environment and an invitation to car thieves.
    2. Remember that children’s health is especially susceptible to vehicle emissions so don’t idle on school grounds, at day cares, at athletic fields or other facilities where you may be dropping off or picking up your children.
    3. In the summer, help keep your vehicle’s interior from getting too hot by using a sunshade. Seek out parking in shaded areas.
    4. Avoid using remote car starters. They encourage you to start your car before you’re ready to drive it, which just means needless idling.

    Is shutting off and restarting my vehicle hard on the engine?

    Restarting just one or two extra times during the day has little impact on engine components. Restarting won’t significantly damage your vehicle since the engine is already warm.

    What else should I know about idling?

    A poorly tuned engine uses up to 15 percent more energy when idling than a well-tuned vehicle. Keeping your vehicle in good condition is a key to fuel efficiency and reduced emissions.
    Idling your vehicle with the air conditioner on (to keep the interior cool) can increase emissions by 13 percent.
    You can improve your gas mileage by up to 3.3 percent by keeping your tires inflated to the proper pressure. Under-inflated tires can lower gas mileage by 0.3 percent for every 1 psi drop in pressure of all four tires. Properly inflated tires are safer and last longer. 

    Information provided by U.S. EPA, Office of Energy Efficiency of Natural Resources Canada, Consumer Reports and Hamilton County Engineer’s Office.