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by mcv 1296 days ago
Why would it not be good to turn your engine off? I sometimes come across stationary cars with a running engine, and I honestly wonder why anyone does that.
5 comments

> I sometimes come across stationary cars with a running engine, and I honestly wonder why anyone does that.

As someone who frequents very warm countries, I think most people do it because of the AC. If the engine is not on, the AC won't adjust the temperature that you've selected.

I have a Volvo hybrid where the AC continues running even when the main ICE is off(as long as you have charge in the main battery pack). It's honestly fantastic.
Hybrid (or PEV/BEV) car's electric A/C is heavily underrated feature compared to pure ICE cars. Idling engine only for A/C seems to really inefficient. I think every police cars should be at least hybrid, but still not here.
Toyota Hybrids do this too and it’s an incredible experience to sit in a parking lot blasting full efficiency AC with the engine off. I’ve heard of people camping overnight in their Priuses this way with minimal engine use.
As a general rule, most machines break during state changes like start/stop. Keeping an engine running means no piece is subjected to the extra acceleration of restarting and your starter isn't used.
You mean besides the constant vibration and acceleration of pistons changing direction multiple times each second?
Yep, which is why diesel cars auto-off/on when stopped is a mixed blessing.

Saves fuel but wears out the battery and starter motor much faster.

A good portion of the mechanical wear and tear on an engine comes from starting/stopping it.
cold starting, actually.

Oil is viscous. It takes time for it to flow down.

I thought cold starting was only an issue in the distant past, and not for modern models.
Time to full lubrication and working temperature has been reduced greatly, but it's still there.
As I understand it, when your car comes off its fast idle (which even at -30 is less than a minute) you're good to gently go now.
probably only when cold.
If you grew up poor a few decades ago, you probably saw your parents begin every journey praying the car would start. Because loads of vehicle faults manifest as failing to start - flat battery, spark plug problems, cold weather, no fuel.

Starting the engine is a stressful experience if you're used to vehicles where sometimes the engine won't start. Especially if you're at the front of a queue of traffic.

It's actually an offence in the UK to do that. Not that it stops anyone.