Why YSK: People seem to, on average, think that a car takes a lot of fuel to start up. In reality, it takes on the order of a few millilitres of fuel to start an engine. That means if your car isn’t equipped with an automatic start/stop system to stop your engine instead of idling, it saves fuel to turn off your engine and start it back up when you need it.
Caveat: air conditioning and radio might not work with the engine turned off.
Scenarios where this might be useful include waiting for trains to pass at rail crossings, waiting for food at drive-throughs, dropping off or picking people up on the side of the road when they need to load stuff, etc. May not be a good idea to use this while waiting at a red light because starting the engine does take time which would annoy drivers behind you when the light turns green.
Some cars are equipped with systems that will automatically stop the engine when you are idling for a while (e.g. waiting for a red light). If yours is, then manually turning off your engine will probably result in reduced fuel savings compared to just relying on the car to do it for you.
Life Pro-tip: don’t turn your car off unless you’re safely parked. Not only is it insanely unsafe, but you’re actively blocking traffic even if it’s stopped around you; in the event of a wreck involving your car in said inert state, you’re in legal trouble in a number of directions. Don’t be a dumbass.
The infinitesimal amount of “saved” fuel is absolutely nothing compared to the mind-bogglingly enormous amount of commercial waste that pushes our civilization to the brink. You’re not “doing your part” in any way at all with this bullshit. Stop already and think, FFS. 🤦🏼♂️
Chiming in to agree that the scenarios listed are mostly ridiculous to think about turning your car off. Knowing that ~7 seconds of idle time is a reasonable threshold for just turning off your car is certainly useful, but how many times has someone turned the ignition key and the car hasn’t started due to battery drain or some other failure? Now imagine that happening at a stoplight, a drive-thru, or a rail crossing.
Seriously, this is some malinformed groupthink. How thafuq does anyone think that it’s safe at any point to be a stationary object in the middle of the damn road?! Assuming your car starts right back up again without any issue (non-zero chance of a wide array of complications there), why would you choose to add several seconds to your reaction time in an unforeseen emergency where a fraction of a single second could be the difference between life or death — and not just your own?! Fuck. This very notion is so disgustingly self-absorbed and short-sighted. Christ on a stick.
In those situations, it’s not going to be a life-or-death situation. The surrounding traffic is going zero miles an hour. Even if someone hits you, they’re going to do it at a couple miles an hour. And since you’re surrounded by other vehicles going at most a couple miles an hour, you’d be hit anyway.
Well, generally, stopping for stoplights, school buses, flaggers, downed trees, or pedestrians is considered a good idea.
Acquaintance of my dad’s was seriously injured a few decades ago when he was rear-ended at a stoplight. It was by a car that had its brakes out and had slammed into the back of his car. It’s a pretty rare chance, but to be fair the person above you is talking about non-zero chances here.
Similar thing also (allegedly) happened to my driving instructor when I was in driving school except it was an 18-wheeler. He had the reaction time to drive out of the way and into the other lane. If his engine were off he likely would have died due to the time it would have taken to start it. I don’t know how real that one is though, it was a story he told all the time.