Idling Away Money: Drivers Can Save Dollars
The average American driver spends over 16 minutes a day, 8 hours a month, 4 days a year idling their vehicle. Much of that idling needlessly burns up fuel and spews out greenhouse gases, says researchers. And costs American motorists 5.9 billion dollars a year.
The findings come from the first-ever survey of US drivers and their idling habits. Researchers at Vanderbilt University in Nashville, Tennessee questioned 1300 people from across the United States about how long and why they idled their vehicles.
Drivers reported that half their idling time was spent in traffic, while stopped at traffic lights or stuck in traffic jams. The rest of idling time occurred while warming up a vehicle before heading out, or while waiting to pick up passengers. Most of this idling outside of traffic is unnecessary, say the study's authors.
US Environmental Protection Agency (EPA) recommends letting a vehicle idle for no more than 30 seconds. Any longer than that, and it's better for both the vehicle and the environment if the engine is turned off.
In the 2007 survey, 92 percent of drivers reported idling for longer than 30 seconds in situations not involving traffic. The survey revealed further that many drivers idle because they hold outdated beliefs about how their cars operate.
Warming Up Cars
With today's fuel-injection engines, cars no longer need warming up. Yet the average driver still believes a vehicle should idle for two minutes before driving in mild weather, and five minutes in cold temperatures.
Half of survey respondents warmed up in fall weather for over 30 seconds, averaging 2.7 minutes a day of over-idling. A driver who excessively warms up their vehicle typically burns through $30 a year, based on average US gas prices in 2008.
Extrapolating the survey results to the country as a whole, if all drivers restricted their warm-up time to 30 seconds, the United States could avoid consuming 2.3 million gallons (8.7 million litres) of gas a day.
Waiting for Passengers
Nearly half, 46%, of drivers in the study leave their car idling for more than 30 seconds while they pick up kids at school, go through a drive-thru, or do other errands. On average, the waiting accounts for over three minutes a day of extra idling, costing a driver 36 dollars in gas a year.
When waiting longer than 10 seconds, though, it saves fuel and is easier on the engine to turn off the vehicle.
Most drivers were way off this mark when asked about the optimum amount time to allow idling. Over 80% of drivers thought, wrongly, that idling for 3 to 5 minutes rather than turning off the engine would save gas, reduce air pollution, or prevent wear and tear on their car.
Besides saving money, cutting down on discretionary idling conserves energy and helps the environment. If American drivers kept to the 30-second maximum idling time recommended by EPA, they would annually save 1.8 billion gallons (6.8 litres) of gas.
They'd also reduce their carbon dioxide emissions by roughly 15.8 million metric tons. That's a significant amount, more than the carbon emitted by the US soda ash, aluminum and limestone industries combined.
Amanda R. Carrico, Paul Padgett, Michael P. Vandenbergh, Jonathan Gilligan and Kenneth A. Wallston. 2009. Costly myths: An analysis of idling beliefs and behavior in personal motor vehicles.Energy Policy. 37: 2881-2888.