Should You Turn Off the Engine at a Red Light?

[LeElliana]

It is not recommended to turn off the engine while waiting at a red light, as this practice does not save fuel. The duration is relatively short, and the fuel injected during restart is roughly equivalent to the fuel consumed during idling. Additionally, it can wear out the starter and shorten the battery's lifespan. Relevant information is as follows: 1. Consider the duration of the stop before turning off the engine. If the stop lasts longer than 2 minutes, it is acceptable to turn off the engine. For shorter stops, there is no need to do so. The engine, being the heart of the vehicle, will suffer reduced lifespan from excessive shutdowns and restarts. Frequent ignition starts also affect the lifespan of the spark plugs. 2. Traffic congestion should be evaluated based on duration. If the idle time is expected to be prolonged, such as during traffic control, it is advisable to turn off the engine. For short-term congestion (e.g., waiting at a red light), it is not recommended to turn off the engine.

[DiAmelia]

Having driven for over a decade, I believe this issue should be considered case by case. Turning off the engine at short red lights in urban areas simply isn't worth it - the fuel consumed during engine restart is greater, plus it increases starter wear. I once tested this on an older model car, finding each start-stop cycle consumed 0.7ml more fuel than idling. Calculating 20 traffic lights daily, you'd only save half a tank annually. For prolonged traffic jams or railroad crossings with 3+ minute red lights, engine shutoff makes sense - but always observe traffic signals in advance to avoid frantic restarts when lights turn green, which might prompt honking from behind. Older vehicles especially shouldn't undergo frequent shutdowns, as their batteries and starters can't withstand constant cycling.

[DiJessica]

Whether to turn off the engine at red lights depends on the vehicle. For new cars with auto start-stop systems, there's no need to worry—the system automatically controls the shutdown duration, and stopping for over 0.7 seconds saves fuel. When driving a friend's Tesla, I noticed the start-stop process was completely vibration-free, but my old Ford's manual shutdown and restart felt particularly jerky. Additionally, never turn off the engine during rain or when using air conditioning, as slowing wipers and interrupted cooling affect safety. Considering the average red light at regular intersections lasts only 45 seconds, it's really unnecessary to frequently restart the engine just to save a bit of fuel.

[AnastasiaDella]

From the perspective of vehicle wear and tear, turning off the engine at red lights isn't worth it. The starter motor of an average car is designed for about 60,000 starts. If you turn off the engine at every red light, commuting 20 times daily would require three starter replacements in ten years. Last time, a mechanic mentioned how they dread owners who blindly try to save fuel—many disassembled cars showed worn-out starter gears. With China's Phase 6 emission standards, modern engines already have very low idle fuel consumption. My car consumes only 0.15 liters of fuel after idling for 10 minutes in tests. Rather than shutting off the engine, regular throttle body cleaning is the real fuel-saving solution.