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How Much Gas Does Idling Use?

The engine is running, but the car is not! Commonly known as car idling, this condition is experienced on a daily basis when you stop at a red light. The other situation could be when you have started the engine but would be waiting for a friend to get in. But the question here is, does the gas get burned while idling? And, if yes, then how much gas does idling use?

Everyone has their perceptions, but knowing the technicality behind the same is important.

First, let’s learn a bit about how the car idles before going to know how much gas is used idling.

How Does An Engine Idle?

So the engine’s idle is firstly set by a simple throttle stop, known as an idle screw. This screw takes its position on the side of the throttle body and stops the throttle linkage arm from completely shutting the butterfly valve that allows air to enter the intake manifold.

The throttle stop allows the butterfly valve to sit ever-so-slightly open, thus allowing for a minimum amount of airflow to reach the combustion chamber. This opening is just enough to allow a specific amount of airflow through to keep the engine running when there is no physical throttle input from the gas pedal.

Then, with the throttle stop being a fairly rudimentary form of creating an idle, the IAC valve uses sensors that talk to the ECU to adjust airflow into the engine to accomplish a desired engine speed at idle. The air that is allowed to bypass the butterfly valve and instead is sucked in via the vacuum within the inlet manifold to keep the idle as stable as possible in differing conditions. The sensors are used to measure factors like ambient temperature and electrical load on the vehicle to then influence the percentage that the IAC valve opens or closes to find the desired engine speed for idle.

So the air and the fuel are the two important ingredients to make the car idle. Since the air is free in space but the fuel is bought by our money. A lot of people do take care about how much gas does a car use when idling or idling fuel consumption per hour. Now let us introduce to you how much gas does idling use. 

How Much Gas Does Idling Use?

While you would be confused between idling and shutting off the engine so that you can restart it again, getting the facts straight becomes important. Read the section below and steer clear on how much gas does a car use while idling.

1. Dependence on Engine Type

The fuel gets burned while idling is a known fact but how much is used, is the question here. A study points out at the fact that the rate of fuel consumption while idling depends from car to car. Generally, an idling car uses somewhere between 1/5 to 1/7 gallon of fuel per hour.

how much gas does a car use when idling
Generally, an idling car uses somewhere between 1/5 to 1/7 gallon of fuel per hour. Source: repareo

Compact cars that carry a 2-liter capacity engine burn around 0.16 – 0.3 gallons of gas on a per hourly basis. A large sedan, on the other hand, with a 4.6-liter engine, burns approximately 0.5 – 0.7 gallons of gas while idling. One should also keep in mind that the diesel engine’s fuel consumption at idle is not much. This is because of the absence of any throttle restriction.

2. Depending On The Objective Things

You may not know but the fuel actually consumed by an engine depends on outside temperature, barometric pressure, engine load (spinning an automatic transmission which even in neutral that needs power) alternator loading—and a bunch of other things, including the technical sophistication of the actual engine.

Another reasonable approximation is that the fuel consumed in 100 minutes will equal the engine size in liters – a little (10%) more in winter or in summer if you turn on the air conditioner. It is how much gas does idling use.


3. Shutting Off and Restarting

Most people believe that when you shut off the engine and restart it when required it would burn more fuel. The situation is completely different when concerned about how much gas does idling use. An idling engine for even around 10 seconds is recorded to use more fuel than the engine restart.

idling fuel consumption per hour
An idling engine for even around 10 seconds is recorded to use more fuel than the engine restart. Source: forcusedcollection

When less idling is involved, less of costs are involved; thus more savings. One should also keep in mind that an engine restart does not cause much of pressure on the engine, but the idling does.

How Does Car Idling Affect Your Ride?

So you already know about how much gas does idling use. But does car idling affect your ride? The answer is yes, car idling isn’t necessarily harmful to your vehicle but it does have effects.

  1. First, it wastes gas. Leaving your engine running consumes gasoline. As a matter of fact, allowing your car to idle for two minutes is equivalent to driving a mile. You can waste almost a gallon of gas if you leave your car idling for more than an hour.
  2. It burns up oil. Longer time leaving your engine running causes more motor oil to be circulated and burned up. This will cost you more money due to more frequent oil changes.
  3. It is bad for the environment. Your exhaust system produces emissions into the air and contributes to air pollution. Sitting in one spot for a long period of time pollutes air.
  4. Also, it decreases performance. Over time, idling can cause your head gasket, spark plugs, or cylinder rings to deteriorate and stop working.
  5. Last, it drains the car battery. Idling does not allow your battery to charge and causes it to strain.

One of the most important effects of idling to keep in mind is the carbon monoxide poisoning. Please do not leave your car idling in a confined space, as it could be toxic to you and your passengers. If you must leave your car idling, then ensure that you’re in an open and well-ventilated area.

Tips to Avoid Car Idling

When at a traffic signal, people prefer to shut down the engine and restart it when the signal turns green. In winters, people prefer to idle the engine so that the car warms up. One should avoid doing that too. The best way to warm up an engine is to drive the car.

how much gas is used idling
When at a traffic signal, people prefer to shut down the engine and restart it when the signal turns green Source: new.qq

Roll down the window or go inside if waiting. Are you waiting to pick your kid up or going through the drive-thru? Instead of waiting in your car, turn it off and head inside! If you can’t go inside, roll down your window and enjoy the breeze. You also can upgrade to a hybrid. Avoid idling all together with a hybrid car! When you come to stop, the gasoline engine shuts off and power switches to the electric motor. This electric motor helps reduce fuel consumption and emission production.

The statistics regarding how much gas does an idling car use; point out at another fact. Idling for about 30 minutes a day for two consecutive winter months can consume a full gas tank. One should avoid idling to reduce the carbon footprint and to save on fuel costs. Read maintenance tips for suggestions on how you can reduce the fuel costs.

Watch the video below to see How much fuel a car use at idle:


Looking at how much gas does idling use; one should always try to avoid it. Be it for saving money or contributing positively towards the environment; avoiding idling can help save the day. Check more other articles about maintenance tips so you will better understand your car and know what to do when needed.