Is It Safe to Sleep in a Car with the Engine Running?

[LaNaomi]

It is not safe to sleep in a car with the engine running. Sleeping in a car after turning off the engine is also not advisable. If you must sleep in a car, ensure the windows are open, the surrounding air is fresh, the temperature inside is not too high, and the car is parked in a safe location. Below are the dangers of sleeping in a car: Over time, the concentration of carbon monoxide inside the car will increase. With the doors and windows closed, the environment becomes oxygen-deprived, leading to worsening carbon monoxide poisoning in the body. In a short period, a person may experience dizziness and headaches, followed by temporary loss of consciousness in more severe cases, and even coma or death.

[DelJace]

Honestly, I have to warn you to be really careful about sleeping in a car without turning off the engine. I've experienced it myself—during a long night drive, I was so exhausted that I pulled over, left the AC on, and dozed off. Within minutes, I felt dizzy and had chest tightness, realizing it was due to poor air circulation causing harmful gas buildup. You know, a running engine emits carbon monoxide, a colorless and odorless killer. Especially when parked in an enclosed garage or with recirculation mode on, the concentration spikes rapidly, risking poisoning or even fatality. Modern cars may have smart ventilation systems, but idling also consumes shockingly high fuel—burning through a lot of money per hour. For safety, it's best to find a rest area or open space to turn off the engine and rest. If you must sleep, keep the windows open for airflow, and never risk doing this in urban or crowded areas.

[LeMarley]

I think this issue is more about health than convenience. Sleeping in a car with the engine running might sound comfortable—cool air from the AC, lying down in cozy comfort—but the hidden risks are significant. When the engine idles, it emits exhaust fumes, especially carbon monoxide and nitrogen oxides. If the air doesn’t circulate well, the concentration of these toxic substances can rise, leading to headaches, breathing difficulties, or even long-term heart issues with prolonged exposure. Personally, I prioritize air quality. After napping in the car once or twice, I woke up with a dry throat and fatigue, which made me understand why experts always advise against it. Moreover, prolonged idling causes excessive engine wear and worsens carbon buildup, leading to costly repairs. If you really need a quick rest, it’s best to park in an open area, turn off the engine, and just run the fan for ventilation for a few minutes—much safer and worry-free.

[Darren]

From an economic perspective, sleeping in the car without turning off the engine is purely wasteful. In idle mode, the engine consumes fuel equivalent to driving dozens of kilometers per hour, essentially burning money for nothing. I once took a shortcut by sleeping in the car with the AC on for half an hour, and calculated that nearly a liter of gasoline was wasted—it hurt my heart. Doing this long-term also accelerates engine wear, causing maintenance costs to skyrocket. There are significant health risks too, as harmful gas buildup affects sleep quality, leaving you groggy and reducing work efficiency. It’s more cost-effective to turn off the engine and rest—saving fuel and staying safe.

[Braxton]

Tried napping in the car with the AC on—feels great but not sustainable. Location is key: parked outdoors with ventilation is okay, but enclosed spaces are too risky due to exhaust buildup and potential poisoning. I often go on off-road trips and occasionally take a quick nap like this, but always keep the windows open for airflow. Idling consumes more fuel and accelerates engine wear, which isn’t cost-effective. In the long run, developing a habit of turning off the engine is better—avoiding hazards while saving money.