Idling Affects Our Respiratory Health: While modern light-duty gasoline vehicles are designed with advanced emission control technologies that have reduced harmful exhaust emission chemicals such as carbon monoxide, nitrogen oxide, sulfur dioxide and benzene, real life factors can inevitably cause increased emissions at idle: vehicle age, how the vehicle is maintained, wear of emission control components and their resulting diminished function, the warmed up state of a vehicle, and how cold the weather. Medium- and heavy-duty commercial vehicles, many equipped with diesel engines and less restrictive emissions controls, cause significantly higher levels of harmful emissions when idling.Prolonged exposure of these emissions affects our respiratory systems, including our lungs and heart. Children, the elderly, and individuals with asthma are especially vulnerable.
Idling wastes fuel: Whether a light-duty car, SUV or pickup, or commercial truck, needless idling burns your hard earned dollars through the exhaust pipe. An idling vehicle gets 0 miles to the gallon. And remember that fossil fuels are being depleted in the face of ever increasing world demand.
Idling Can Cause Needless Engine Wear
- Light-Duty Gasoline Or Diesel: excessive idling causes needless engine wear that can lead to increased engine maintenance and shortened engine life.
- Heavy-Duty Diesel: excessive idling causes increased engine maintenance and shortens engine life . Manufacturers of these engines, including Kenworth Truck Co., Caterpiller, Inc., IC Corporation and Cummins Inc., advise operators to limit idling to a maximum of 3-5 minutes.
Idling Poses a Threat to our Security While Wasting Energy: The Obama-Biden administration’s Energy and Environment Agenda calls for an end to America’s addiction on foreign oil. President George W. Bush stated in his 2006 State of the Union address that America is addicted to oil. Both administrations have agreed that our dependence on foreign oil poses a threat to our economic and strategic security. Idle reduction is part of the formula to help make Wyoming and America energy independent.
Idling Causes Noise Pollution: In our town centers, cities and suburbs, many agree there’s already enough noise without having to hear the constant idling of parked vehicles.
How long should a warmed up, parked vehicle idle?
Light-Duty Gasoline or Diesel (car, SUV, pickup): The overall recommendation for a ‘cut-off point’ is 30 seconds. Actually, any more than 10 seconds of idling uses more fuel than is required to restart the engine. However, the break-even time to offset any potential incremental maintenance costs to the starter or battery is 30 seconds. So, as a guideline, if you’re stopped out of traffic for more than 30 seconds – turn off your engine.
Heavy-Duty Diesel (commercial trucks and buses; school buses): The EPA, American Trucking Association, and several diesel engine manufacturers  recommend 3 to 5 minutes to allow for turbo cool-down after full load operation. Engine manufacturers also recommend to shut down and restart up to several times a day rather than continuous idling to save fuel and engine wear. 
How long should a vehicle warm up from a standstill?
Light-Duty Gasoline or Diesel: check your owners manual for any specific recommendations, but some good rules of thumb are as below.
Above freezing temperatures: typically no need to warm-up at standstill; the best way to warm up is to drive the vehicle at a moderate pace.
Below freezing but above 0 degrees fahrenheit: up to 30 seconds to allow for complete circulation of engine oil. Warm-up time is also determined by the effectiveness of defrosting. Again, driving the car (slowly to moderately) is the best way to warm up in this range. Note that wheel bearings, steering, suspension, transmission and tires also need warming up. The only way to do that is to drive the vehicle. A possible exception to the 30 second rule is if vehicle occupant(s) are very elderly or an infant in below freezing temperatures – then cabin temperature will need to be brought up.
Below 0 degrees: in this range, idling the engine for a period of 1 to 3 minutes becomes more important, allowing thickened engine oil to adequately circulate throughout the engine, and for the likely increased time needed for defrosting/deicing.
Heavy-Duty Diesel: the EPA and several diesel engine manufacturers recommend no more than 3 to 5 minutes . But there are idling reduction alternatives to consider. Use electric engine heaters (such as block heaters) to minimize idling time during warm-up, especially in cold weather. Install a small generator or auxiliary power unit specifically designed for a truck that provides heat, air conditioning, and/or electrical power while the vehicle is not in motion. These devices are a better, more efficient alternative to idling as they use substantially less fuel and emit less pollution. Depending on the amount of time spent idling each year, the payback on these devices can be one to two years.
Recommended cold weather warm-up procedure for light-duty gasoline engines
Make sure that your vehicle is tuned-up. Except in below 0 conditions, avoid remote vehicle starters which encourage excessive idling. Consider use of an engine block heater which can be timed to turn on one to two hours before starting the engine. They allow less strain on the starter and battery, can lessen stationary warm up time in extreme cold, and allow the vehicle to consume less fuel during warm up driving. Protect yourself adequately from the elements with warm clothing. Be prepared with window scrapers that work. Consider the use of a can of spray de-icer or make your own solution of half water and half vinegar in a spray bottle. When necessary, scrape/de-ice and clear your vehicle off before starting. Then start the engine and immediately blast the defroster. In most cases, you’ll be ready to go in 30 seconds.
- American Lung Association
- Translated from Natural Resources Canada CO2 emissions calculation on idling
- Governor’s Commission on Climate Change
- U.S. EPA SmartWay Vehicles
- U.S. EPA Clean School Bus USA National Idle-Reduction Campaign: Engine Wear-and-Tear
- EPA New England: “What You Should Know About Truck Engine Idling” “Running an engine at low speed (idling) causes twice the wear on internal parts compared to driving at regular speeds. According to the American Trucking Association, such wear can increase maintenance costs by almost $2,000 per year and shorten the life of the engine.”
- Crackdown On Idling Time
- U.S. Dept. of Energy: “The best way to warm up a vehicle is to drive it. No more than 30 seconds of idling on winter days is needed.”