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.

It's not necessarily an issue of fuel, but the overall wear on the components and engine when you start a car. A starter motor only has so many "starts" it can do before dying. The battery too.

Starter motors have gotten a lot better since the "bad old days" and engines start more smoothly thanks to fuel injection and computer control systems, so manufacturers have decided that it's ok to start/stop engines as needed, but the reason for not doing it was never a matter of fuel savings.

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 the engine puts as much wear on it as driving for 50 miles. Automatic start/stop hurts engine longevity by doing that unnecessarily and should always be turned off.

My car uses 0.5l of fuel idling for an hour. There's no way in hell that a start/stop system would even save 10$ a year, so there's no benefit to using it.

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. 🤦🏼‍♂️

Mild-hybrid cars with 48-volt batteries (instead of the standard 12 volt) can pretty seamlessly stop and start the engine to where you don't even feel it, and easily power the AC and radio and everything else while the engine is off.

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.

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.