How Long Can I Leave My Car Running While Parked?

Busy moms can all relate to the struggles of leaving the house to run errands with the kids in tow. Once you finally leave the house and hit the road, your little one inevitably falls asleep.

When you reach your destination, you may be wondering how long you can safely leave your car running while parked to jump out and run a quick errand without disturbing the peace. 

On average, car ideal longer than 5 minutes will cause the engine to go over normal temperature. Many states limit ideal time to 20 minutes during cold temperatures. If you must ideal try to drive the car around the block after every 5 mins. 

The exceptions are hybrid or electric vehicles since they use electric motors while idling instead of gas. 

While technically, you could potentially keep your car running for several hours until you run out of gas, it doesn’t mean you should. This article will explore why that is, what instances it’s okay to leave your car idling, and ways to reduce idling when possible.  

What Is Idling Anyway? 

Idling refers to running a vehicle’s engine at a lower power while the car is not in motion. When the engine is active, but the car isn’t moving, the vehicle is idling. 

When Is It Okay To Leave My Car Running? 

Sometimes you can’t avoid idling. If you’re stuck in traffic, at a stoplight, or in the line for school pick up, chances are your car is running. Maybe you need to warm up the car’s engine and interior on a cold morning. In instances like these, it might make more sense to leave the vehicle running for a short period. 

Likewise, the busy mom in our example above may be okay running to the ATM or into the UPS store to drop off a package while leaving the car running, but for anything longer than a quick errand, it’s better to switch off the engine. 

If you need to leave your little one in the car for a quick errand on a hot day, it’s important to make sure they are comfortable. If you don’t want to blast your AC, you should always try to park in the shade with the windows rolled down if you can.

It’s also a good idea to invest in a sunshade or small battery-operated fan that can easily attach to car seats and strollers.

Why Should I Avoid Idling?

When possible, you should avoid idling your car for extended periods and try to be mindful of when and how often you’re doing it. Below are some of the reasons you might want to think twice before leaving your car running. 

It Wastes Fuel 

It’s a common misconception that stopping and restarting your engine uses up more gas than idling. According to the Environmental Defense Fund, you will use up the same amount of fuel, stopping and restarting your vehicle as you will with ten seconds of idling.

Thanks to fuel injection technology, drivers no longer need to worry that stopping and restarting their cars will waste fuel. If you stop for more than a minute, you can save fuel by turning off your engine instead. And with the cost of gas today, restarting is by far the best option. 

It Can Be Hard On Your Engine

Idling for an excessive amount of time can wreak havoc on your engine’s parts, including your exhaust systems, cylinders, and spark plugs. The reason behind this is because when your car is idling, the fuel is only partially combusted.

Because of this, it can lead to buildup on the cylinder walls leading to damage to spark plugs and exhaust systems. 

It’s Harmful To The Environment

Carbon dioxide is the number one contributor to global warming and is released through car emissions when idling. So every ten minutes that your engine is off, you’ll prevent one pound of carbon dioxide from being released. 

Therefore, if you’re concerned about the air that your family is breathing, it’s a good idea to limit the amount of time your car is running. 

It’s Harmful To You And Your Family’s Health

As tempting as it may be to leave the car running while you run inside the store or bank, it might not be the best choice for your little one’s health. Did you know that when you’re idling, exhaust air can seep in through the vents?

Excessive carbon monoxide exposure can lead to an increase in your and your family’s risk of developing or worsening some dangerous conditions such as asthma and allergies. It can also increase your risk of developing heart and lung disease, cardiopulmonary disease, and even certain types of cancers.  

You May Run Out Of Gas

If you’re running on low, you may want to think twice about idling for an extended amount of time, as this may put you at risk of depleting your fuel tank. The last thing you need is to run out of gas on the way to school pickup. 

You Can Invite Theft

It’s something we don’t ever want to think about, but the fact is that there are thieves out there. Car theft is on the rise in many cities around the US, and unfortunately, idling cars can make for an easy target.

A stolen vehicle is never something you want to deal with, but it’s a mother’s nightmare if children are inside. 

If you choose to leave your car running, always make sure you have a clear view of your vehicle and are able to get back to it quickly in case of an emergency. 

Your Car Battery Could Drain 

If you leave your car running, it consumes power from your car’s battery—the engine and alternator run at a slower pace when your vehicle is idling. The alternator will have enough power to charge the battery.

However, if you’re running an AC, heater, or any other electrical components such as lights or your radio, this could cause your battery to drain much faster. 

It Could Be Illegal

Some US states such as New York, Massachusetts, Hawaii, and parts of California have passed laws making idling illegal. Other countries have followed suit. Unnecessary idling could result in a fine, so it’s best to switch off your engine when in doubt. 

Are There Times I Shouldn’t Leave My Car Running?

You should never leave your car running while pumping gas at the fuel station. The fumes that gas pumps emit can easily ignite due to their high temperatures, so always make sure you turn off your engine completely while filling up your tank. 

It’s also never a good idea to leave your car idling in the garage, especially when the garage door is down or if family members are in the vehicle. Dangerous amounts of carbon dioxide can enter the car and lead to poisoning or even death. 

What’s The Deal With Hybrid Or Electric Vehicles?

There is good news for clean air vehicle owners. If you drive a hybrid or electric vehicle, you don’t need to worry as much about idling.

When you idle, the gas engine shuts off in hybrid cars, and your power switches to the electric motor, reducing both your emission production and fuel consumption. Since electric vehicles (EVs) only run on electricity, they have 0 emissions and only use the electric motor. 

Since hybrids and electric vehicles are quieter when powered on than traditional vehicles, remember to switch the engine off from idling to prevent draining the battery. 

Common Misconceptions About Car Idling 

Over time, you’ve probably heard many myths about idling. Below we’ll clarify some of these common myths and provide tips to prevent yourself from idling too long and too often. 

You Need Your AC Or Heater When Parked 

Instead of idling while running your AC or heater, consider bringing along a hat, gloves, and a warm drink for cold days or a personal fan for warm days. If the outside temperature is lower than your car, turn off the engine and open up the windows to get a nice breeze. 

You Need To Warm Up Your Engine In The Morning 

Many people living in cold weather climates don’t realize that it’s unnecessary to “warm-up” your engine and interior for a significant amount of time. Turning your car on for 30 seconds before you start driving is typically plenty of time for modern vehicles, and your vehicle’s interior will warm up even more once you start driving.

As another alternative, consider driving around the block to warm up instead of leaving the car running unnecessarily.

It Saves Fuel To Idle 

As mentioned above, we’ve learned that modern vehicles don’t need to idle to save gas. So when you idle for even longer than 10 seconds, you could actually be wasting valuable fuel. 

Final Thoughts 

While sometimes, we can’t avoid idling, it’s a good idea to be aware of how long and how often we tend to leave our car running without a second thought. After all, the consequences could be more significant than we realize. 

The next time you find yourself waiting in the school pickup line or at the drive-through coffee window, consider turning off that engine instead of leaving the car running. Not only will you be putting less strain on your pocketbook, but you could be doing your and your family’s health, the health of the planet, and your vehicle a favor.