[pedro_hab]

I wonder if the lower emissions are really worth it if the car breaks down sooner.

All the electronics and gimmicks to lower immediate emissions at the cost of reliability.

My car, for instance, turns off the engine when stopped, that can't be good for the engine and battery.

If saves a bit of gas but I am sure I'll have to change my battery sooner, not to mention the wear and tear on other components.

[ljf]

Diesel engines in particular, do not like being run under no load - it is far far better to have them switched off rather than running. Boat owners struggle with this when moored, as they can't charge their leisure batteries by just running the the engine without engaging the prop.

I don't know anyone with a stop/start engine that has ever complained to me about having to replace their battery sooner. Personally, I drive clunkers, and have never had to replace a battery on one of those, despite me turning off the engine whenever I can. I think modern batteries are pretty damn hardy.

[scrumper]

Yeah. While the instantaneous power draw is absolutely colossal, the actual energy drained from a battery starting a (healthy!) engine is fairly minimal, and its replaced very quickly by the alternator once it's up and running. Stop/start engines also use the ECU to stop the engine at the right point in the compression cycle for it to fire immediately, without cranking, so there's even less drain. (Even pre-stop/start engines in cars with modern ECUs tend to leave them in a position where they fire almost immediately.)

What kills batteries is deep discharge cycles. Sipping a bit of juice to start an engine and replacing it quickly does almost nothing to reduce its lifespan.

[Tade0]

> My car, for instance, turns off the engine when stopped, that can't be good for the engine and battery.

It's largely irrelevant.

More than half of the wear and tear in an engine happens during cold starts. Unless you're in utter gridlock, you won't experience them more often than when at the start of the trip.

Toyota's hybrids turn the engine off and on on a regular basis, even during cruising, and have a proven track record of reliability.

[gambiting]

>>My car, for instance, turns off the engine when stopped, that can't be good for the engine and battery.

A friendly reminder to everyone on the internet that your instinct and "gut feeling" isn't worth all that much. It's trivial to find out stats on this, and they prove that the inclusion of Start&Stop systems in cars had zero impact on reliability since their introduction over 10 years ago. But I still see people on forums saying "this can't be good for the engine!".

[jsolson]

> My car, for instance, turns off the engine when stopped, that can't be good for the engine and battery.

I understand the intuition behind this, but one could also see a place where starting the engine while it's still hot is better than idling (less wear, fewer opportunities for deposits to build up from wasted combustion), and where the impact to the battery is minimal as the hot engine makes it easier to turn over for the very few cycles it takes to get it going again.

[snovv_crash]

It isn't about heat, it is about the main crank bearing which is a fluid bearing that needs oil pressure to work. When your engine isn't running there isn't sufficient oil pressure so the first few revolutions are pretty tough on the engine. Hot is actually worse because the oil that is there is thinner and more likely to result in metal on metal. Engineering an ICE for an order of magnitude more starts is probably mostly upgrading the battery, starter motor, and main crank bearing.

[calvinmorrison]

they coat the cranks with a special polymer to help with start/stop and hybrid engines that undergo frequent cranking

[ezfe]

A Prius starts and stops the engine constantly while driving, not just stopped - and they are known for lasting a very long time as well

[mcv]

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.

[capableweb]

> 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.

[gambiting]

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.

[fomine3]

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.

[radicaldreamer]

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.

[belval]

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.

[drcoopster]

You mean besides the constant vibration and acceleration of pistons changing direction multiple times each second?

[emmelaich]

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.

[zxexz]

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

[Tade0]

cold starting, actually.

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

[mcv]

I thought cold starting was only an issue in the distant past, and not for modern models.

[Tade0]

Time to full lubrication and working temperature has been reduced greatly, but it's still there.

[SketchySeaBeast]

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.

[canbus]

probably only when cold.

[michaelt]

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.

[zelos]

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

[NavinF]

I was with you until "turns off the engine when stopped, that can't be good for the engine". That was a concern in the mid 2000s when start-stop hybrids were just starting to become mainstream. Today nobody notices or cares because the concerns never materialized.

[cowmix]

My 2013 Volt has 150+ K miles - the engine runs like new. I've never touched the brakes, only 2 oil changes, etc.

[belval]

Regenerative breaking is an amazing piece of tech. I really like electric cars that have it baked-in the "gas" pedal so that releasing it slows down the car without using the brakes. You can achieve "optimal" driving by always recouping the kinetic energy as electricity instead.of heat in your break pads.

[vel0city]

Most of my EV driving is in single pedal mode. I absolutely love driving in this mode. I feel like I just have far more control over the vehicle by having a single pedal to directly control the speed instead of the vehicle just rolling when I get off the accelerator. Also, the fact the car just stays put when stopped instead of constantly rolling forward in drive is really nice.

Sometimes my car loads my wife's profile when I drive which changes it back to standard driving. It is jarring having the car just always want to roll forward. It just feels so much worse than single pedal driving.

[frosted-flakes]

I'm assuming the standard driving profile imitates an automatic transmission with a torque converter, which continually creeps forward if the brake isn't held down. As opposed to a manual or dual-clutch automatic transmission, which does not creep (except by gravity).

Is disabling this "creep" independently of braking with the gas pedal an option in any electric vehicles? I seem to remember that some cars with continuously variable transmissions had this as an option.

[vel0city]

There is still often an "Auto Hold" feature that will engage the brake when the vehicle comes to a complete stop. My EV can have auto hold engaged while not being in the single pedal drive. I have this in my ICE as well, but it doesn't seem as smooth overall, so I don't end up using it much.

It is still not quite the same experience though, as the ICE will just keep rolling at low speeds forever without actually ever coming to a stop until you press the brake. Auto hold will only engage when the vehicle actually stops. For my EV, when I get off the accelerator pedal it'll come to a complete stop on its own and then hold itself there.

Other than turning on my EV, most trips don't involve me touching the brake pedal at all.

[thatfunkymunki]

On Teslas, I believe the creep setting is independent of the coasting/regenerative braking setting.

[ezfe]

Tesla's have the unfortunate downside that they refuse to enable regen braking through the brake pedal, even as an option

[twobitshifter]

Sometimes the autostart can be an annoyance but newer cars have got it down to almost imperceptible. The restarting shouldn’t be rough like a cold start.