Idling vs turning off your car in traffic — Which is better?

If you’ve been stuck in traffic for quite some time, you may contemplate a few things about life, and about how horrid your fuel economy is going to be after you get out of a jam. While we can’t help you much with your contemplations about life, we can help you answer the other question related to fuel economy. 

Is it better to turn off my engine at a stop to conserve fuel, or is it better to idle? 

As a general rule for turning off your vehicle, don’t let your car idle for more than 10 seconds. Doing so will cost you more fuel than stopping and starting your car up again. Also, it helps the environment by not letting toxic fumes out into the atmosphere. Idling less will also help you preserve the longevity of your car, albeit only making a minor difference. However, doing this continuously can take its toll on your car’s battery as well as its starter motor. The added stress will degrade these parts, but the longevity hit will vary on the vehicle that you have. 

However, there are certain cons to this line of action. For one, if your car’s battery is on its way out, then you might want to reconsider turning your car on and off again. If you have a bad battery in your car, you might end up stressing it too much to the point where it won’t start back up again if you try and turn the key. 

Then we get into the comfort part. Turning off your vehicle will undoubtedly turn off all the other auxiliary systems in it. These systems include air conditioning, infotainment, and other electric components unless you leave them in accessory mode. 

On top of that, let’s not forget the hassle of having to turn your car on again once the stoplight turns green. If you’re crawling in slow-moving traffic, it’ll also be a bad idea to turn off your car in the middle of a slow section of the road. 

Though, the fuel economy gains can be quite negligible the smaller your vehicle’s engine is. For most small hatchbacks with small-displacement engines, it seems a bit much to turn off your motor every time you come to a stop. For bigger SUVs, crossovers, and sportscars, it makes more sense. 

A more common practice compared to turning your car off on the road while at a stop, idling is what most people do anyway if they’re stuck in traffic. Leaving your car’s engine on will allow its systems to remain open and active while at a stop. This means that the A/C won’t turn off, and neither will the radio. Of course, the tradeoff is that you burn more fuel while waiting and your fuel economy will take a hit. 

Another thing to consider, however, is that your car could overheat in traffic when sat for long enough. If your cooling system isn’t as good as it once was, your engine’s coolant temperature might climb up. Even if your engine’s cooling system is up to spec, temperatures will still rise regardless due to the ambient temperature and the other cars radiating heat. 

Though, once the light turns green, you’re ready to go. Just shift or let your foot off the brake and you’re set. 

Manufacturers cannot deny that turning off an engine will undoubtedly save fuel, but this comes at the expense of having the other systems turned off. On top of that, it’s not so straightforward to get up and running again. 

You can find these features in more premium automobiles, but brands like Mazda and Toyota, to name a few, have been trickling this feature down into the more affordable realm. This results in their automobiles becoming more and more economical, especially in traffic-filled cities. 

As such, the start-stop feature was born. Several systems are in place that allows the vehicle to stop idling, keep the air conditioning on, and the other electrics of the car on. Then, when it is time to get up and go, the engine comes to life if the driver decides to put his foot off the brake, or steps on the gas slightly. It’s the best of both worlds.