Idle reduction describes technologies and practices that reduce the amount of time that engines idle unnecessarily. Each year, U.S. passenger cars, light trucks, medium-duty trucks, and heavy-duty vehicles consume more than 6 billion gallons of diesel fuel and gasoline—without even moving. Roughly half of that fuel is wasted by passenger vehicles.

Reducing idling time has many benefits, including reductions in fuel costs, engine wear, emissions, and noise. Engines idle for a variety of reasons, such as to keep vehicles warm, operate radios, or power equipment.

Idle reduction strategies can dramatically reduce emissions of carbon dioxide, nitrogen oxides, carbon monoxide, particulate matter, and other harmful pollutants.

Idle reduction strategies also reduce noise pollution. In some areas, heavy-duty trucks and trains are required to limit noise at night. By reducing idle time, drivers can meet noise standards.

Argonne National Laboratory estimates that more than 650,000 long-haul heavy-duty trucks idle during required overnight rest stops every day. Reducing the amount of fuel wasted on idling can provide significant cost savings. In addition, many idle reduction technologies can improve driver comfort through improved climate control, support for lighting and electronics, better air quality, and reduced noise levels.

Using idle reduction strategies to reduce fuel consumption reduces U.S. dependence on imported petroleum and increases energy security.

Idle reduction technology allows engine operators to refrain from long-duration idling of the main propulsion engine by using an alternative technology. Heavy-duty truck drivers can choose from a variety of equipment to reduce idle time and save fuel.

The U.S. Environmental Protection Agency’s (EPA) SmartWay Program and the U.S. Department of Energy (DOE) have evaluated the fuel-saving benefits of various idle reduction technologies. Both agencies provide information about grant funding that may be available for installation of qualifying equipment. EPA’s SmartWay Program offers a list of Verified Idle Reduction Technologies.

These technologies include:

• Onboard idle reduction equipment
• Truck Stop Electrification Sites

For a database of laws applying to all types of on-road vehicles, see Clean Cities IdleBase.