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.
Caveat: For cars not equipped with automatic start/stop, the starter and possibly the battery might not be specced for it so it could cause additional wear. Cars with start/stop systems often assist the process with precise camshaft position measurements and the ability to squirt fuel pretty much right away so the starter doesn’t need to do as much work.
Also don’t do it with a cold engine - it’s better to get the oil up to temp faster, it’ll also reduce fuel consumption as the engine heats up.
I walk, cycle, or longboard places whenever possible, and when these automatic cars started coming out, I thought they were manually starting and stopping their cars at each intersection. It really tripped me out.
Cars with start/stop systems often assist the process with precise camshaft position measurements and the ability to squirt fuel pretty much right away so the starter doesn’t need to do as much work.
I always wondered why hybrids could start their engines instantaneously, when many conventional cars couldn’t. This is why, isn’t it?
Yeah new cars usually have the ability to do that themselves and also usually do it when safe.
They auto start when power is needed or if the situation changes. Eg: touch the steering or gas pedal. Another example is my car will auto start it too many cars are around me.
Shutting your non-auto starting car off and then having an emergency happen could land your ass in trouble with insurance and the law. If you’re on the road, your car should be running (unless it was designed this way). Of course people mentioned wear and tear, so that too.
Cheers -Henry
Starting and stopping a car is the worst thing you can do to it, doing it repeatedly on purpose is just asking for expensive problems, like a burnt out starter, missing or worn teeth off the flywheel, broken stater mount on the block, dead batteries, coked up and worn out turbo bearings, bearing and knock issues due to lack of lubrication, soot buildup in diesel engines, failed emissions systems, etc.
The few pennies you save in fuel is not worth it, upping the time to 5 minutes would make more sense.
In some cities in my country (maybe all) it is regulated and fined to idle your car over 1 min, the point of it I think is to make people used to turning off their cars for train crossings and bridge openings.
The whole world has weighed in and explained why more starts and stops lead to excessive wear, but I’d like to take a moment and bring a little attention to the environmental damage that having to do a bunch of work to your car because you turn it off at every opportunity does.
Let’s say you need a new starter motor early. That’s copper, aluminum, iron, steel and a handful of rare earths for the solenoid. Melt em, smelt em, form and mold em, that’s more carbon from building the replacement part than you’d have kept out of the atmosphere by shutting off the car at stoplights.
The greenest car parts are the ones already in it.
