Should You Turn Off the Engine When Waiting at a Red Light?

[JaxsonDella]

If the waiting time at a red light exceeds 2 minutes, you can turn off the engine; if the waiting time is very short, you may choose not to turn it off. Here are some precautions regarding waiting at red lights: 1. When waiting at a red light at an intersection, use neutral gear plus the handbrake, as this minimizes damage to the car in case of a rear-end collision. 2. During long waits at red lights, drivers may become impatient and start hastily, neglecting observation, which can lead to danger. Therefore, try not to get distracted while waiting at a red light, and always observe both sides before starting. 3. During early morning or evening when traffic is relatively light, especially on roads where large vehicles are common, continuously check the interior rearview mirror when the car is stopped to prevent being unable to brake in time when encountering other vehicles.

[McHarley]

Last time I chatted with an experienced driver about this, he's been driving a taxi for thirty years and said whether to turn off the engine at red lights depends on the duration. Many cars nowadays have auto start-stop functions that automatically shut off the engine when stopped, saving fuel and being eco-friendly. But I've observed that for manual operation, turning off the engine for red lights shorter than 30 seconds is completely unnecessary, as frequent restarts can harm the battery more. In summer, if you turn off the engine with the AC on, the cooling stops immediately, making the car stuffy and uncomfortable. It's really worth turning off the engine for those extra-long red lights over 90 seconds, like at major road intersections. Once, I turned off the engine at a main city road light, only to be honked at by the car behind, flustering me—so traffic flow matters too.

[LaPresley]

As a driver who frequently takes long-distance trips, I believe it's important to calculate the economic benefits. Shifting to neutral and releasing the throttle 15 seconds before a red light can save 40% more fuel than idling. If you're considering turning off the engine, it's only worth doing for lights longer than 60 seconds. Otherwise, frequent cold starts can increase wear and tear. This is especially important for older cars—don't push your luck with an aging battery. Once, I tried it in a friend's old Jeep: turning off the engine three times for 20-second red lights, and ended up with a dead battery needing a rescue. Drivers with auto start-stop systems don’t need to overthink it—the system knows better when to shut off the engine.

[ElliottRose]

My Hyundai has an intelligent start-stop system. The engine shuts off when I press the brake pedal firmly and automatically restarts when I release it, which is especially fuel-efficient in traffic jams. However, some owners turn off this function for fear of damaging the engine, but it's actually unnecessary. Car manufacturers have already considered tens of thousands of start-stop cycles in durability tests during the design phase. Just remember not to let the engine shut off in rainy or waterlogged areas, as water entering the exhaust pipe could cause issues. For short red lights, it's recommended to keep the air conditioning and radio on, as these devices would need to reset if the engine suddenly shuts off and restarts.

[LorenzoDella]

An apprentice at the repair shop once asked the master about this, and the master said it mainly depends on three things: the car's age, battery life, and the duration of the red light. For new cars under three years old, it's fine to turn off the engine anytime, but older cars need to be more cautious. Starting slowly when the light turns green might get you honked at by the car behind. One detail often overlooked is that turbocharged cars shouldn't be turned off immediately after a high-speed run—it's bad for the turbo. Instead, they should idle to cool down at red lights. Personally, I only turn off the engine if the red light lasts more than 45 seconds; for shorter waits, I just step on the brake and listen to some music.

[EllianaFitz]

Commuting through eight traffic lights daily, personal testing shows that turning off the engine saves fuel but costs mental energy. Manual transmission cars are the most troublesome, requiring clutch engagement, ignition, and gear shifting. Slow operation when the light turns green easily invites honks from cars behind. It's recommended for beginners to first familiarize themselves with the location of their car's start-stop button. During rainy or foggy weather, it's best to keep the engine running to maintain lights and wipers. Additionally, old urban areas have many short red lights. Rather than frequently turning off the engine, turning off the air conditioning to reduce load is more practical.