Does it waste gas to idle? The answer is yes, obvious right? Not for a lot of people.
Many people have been taught that if you are going to idle for less than a minute, it is better to keep the car running. That is simply not true. As you can see in the video that when I stopped at the light my gas mileage was 36.2 MPG. By the time the light changed it had gone down to 35.5 MPG. In other field test’s where I have turned the engine off at a light, the mileage did not change once I started it up again.
According to the California consumer energy center ” If you’re in a drive-through restaurant/business line or waiting for someone and you’ll be parked and sitting for 10 seconds or longer… turn off your car’s engine.”
Wayne Gerdes in his article on the “why’s and how to hypermile” says ” Consider shutting down your vehicle if stopped for more than 7-seconds as that is all the fuel it takes to restart a modern day, fuel-injected engine.”
The lower gas mileage you get, the more of a difference it will make. For instance my 2007 Honda Civic rated at 25 mpg city uses .19-.22 gallons per hour when the engine is idling. A 2013 Chevrolet Corvette rated at 15 mpg city will use perhaps twice that amount.
How much money do American’s waste each year due to idling?
A new study by the U.S. Treasury Department finds that traffic snarls wasted 1.9 billion gallons of fuel last year — about 5% of the gas American motorists used. At the current price, that would work out to more than $7 billion nationwide.
Here are some other myths associated with idling according to the California consumer energy center
Myth #1: The engine should be warmed up before driving. Reality: Idling is not an effective way to warm up your vehicle, even in cold weather. The best way to do this is to drive the vehicle. With today’s modern engines, you need no more than 30 seconds of idling on winter days before driving away.
Myth #2: Idling is good for your engine. Reality: Excessive idling can actually damage your engine components, including cylinders, spark plugs, and exhaust systems. Fuel is only partially combusted when idling because an engine does not operate at its peak temperature. This leads to the build up of fuel residues on cylinder walls that can damage engine components and increase fuel consumption.
Myth #3: Shutting off and restarting your vehicle is hard on the engine and uses more gas than if you leave it running. Reality: Frequent restarting has little impact on engine components like the battery and the starter motor. Component wear caused by restarting the engine is estimated to add $10 per year to the cost of driving, money that will likely be recovered several times over in fuel savings from reduced idling. The bottom line is that more than ten seconds of idling uses more fuel than restarting the engine.