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Comment by Angostura | Hacker News Reader

Not mentioned in the article, but I imagine that this could be exacerbated by the fuel-saving 'auto engine off' behaviour of newer cars... you arrive home, engage the brake and the engine turns off automatically.

... only to automatically restart 15 minutes later when the engine sensors detect the oil temp is dropping.

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This happened to me with a hire car. I parked the car and pressed the button to stop the engine. The engine cut out so I got out of the car, locking the vehicle with the remote as I walked away. After some time I was contacted by the security team of the company I was visiting to tell me the engine was running on my vehicle. The auto engine off had kicked in as i pressed the engine stop button, but because the engine had stopped I didn't hold the button for long enough to actually switch the engine off. When I locked the car the turn indicators flashed with a non-standard pattern to warn that the lock had failed (because the engine was not off) but because it was a hire car I did not recognise it. When I drove the car home the same thing happened at the end of the journey but this time I was expecting it and switched the car off properly.

Did the dashboard display and lights go out and did it not emit a tone when you opened the door?

There was no tone when I opened the door, not that I heard anyway (it was a 2017 Citroen C4). The dashboard may have stayed lit but as it was a hire car I had no idea what the normal behaviour should have been. I had two passengers who also did not notice anything out of the ordinary when we left the car. A colleague had the same thing happen in a C4 but he was still in the car when the engine restarted.

It just occurs to me that this is probably only an issue with automatic cars since any shift car will just have the engine die immediately if you start it with the shift pedal unpressed.

No. (I drive a manual shift car in the UK). If you stop the car, put it into neutral and press the foot brake, the engine will stop if conditions are correct.

I have been taught to always put the first gear in when parking the car, that's where that idea comes from. If you leave it in neutral, I am indeed wrong.

It won't be the same for all, but my car won't autorestart the engine if I've opened the door i.e. the behaviour changes from

- pull up, shift to neutral, engine stops - wait - car worries about battery, restarts engine

- pull up, shift to neutral, engine stops - open door and get out - wait - get back in, engage clutch, car tells me I have to manually restart the car

> my car won't autorestart the engine if I've opened the door

Ah, interesting - I've never tested that, but it would make sense.

My car has the start-stop technology and the engine always starts up when I put it in park if the system switched it off when I stopped on my driveway. It will also start again if you open the doors while in drive.

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