UKC

Engine idling has been in the news quite a lot lately... And its led me to wonder, why are people so reluctant to turn off their cars when they're parked up waiting? Some reasons that occur to me:

1) Belief that turning the engine off for 2 mins then turning it on again is bad for the engine. [I don't think this is valid in most cases, but I'm sure its complicated and depends on the whole duty cycle of your engine etc etc]

2) Desire to keep A/C or heating running while stopped. Possibly understandable in extreme conditions, but for most 2-5 min stops this is not necessary.

3) Extreme laziness: can't be bothered to turn the key/push the button.

4) Desire to keep 'peripherals' in the car running, e.g. phone charger.

Any other suggestions? 

5) Listening to the radio/ to music and believing that doing that with the engine off will flatten the battery

6) Not giving a toss about the environment, or about people having to unnecessarily breathe the toxic fumes from your car

PS I think your number 1) is a major reason for many people

I don't know about it damaging the engine but I was once told that starting up the engine was bad because it uses up more fuel than idling so to only turn off the engine if you are sat for more than 3-4 minutes.

Might be entirely wrong...

It's extremely common where I live and as the air quality is already really poor, I hate it.

Worst offenders appear to be the contractors on the building site next to me, in company vehicles. Sometimes they do it for around half an hour which seems mad to me.

Although some Home Office vans were parked up not far away the other day as I walked to the station (the types that do immigration raids) and they were doing it too.

In a modern engine that can't be right. Mine takes even a 5 second opportunity to turn itself off and then back on again automatically at lights. I realise this may be naive but I like to think they wouldn't have added that feature if it increased fuel usage.

I could believe that it puts more wear on the battery as that's what bears the brunt of the burden in starting the car, but don't see a reason for a fuel problem.

That one's usually easy to deal with: turn the ignition off, then turn it on again but don't start the engine.  Radio, lighter/USB sockets etc will usually work.  (Description only applies to key ignition.  Not sure how it would work with keyless, but then I believe that to be the work of the devil anyway.)

My car has stop-start which keeps everything else "live" (including the A/C I believe) when it stops the engine.

You also forgot:

5) Active disregard for the law.  See Highway Code Rule 123:

The Driver and the Environment. You MUST NOT leave a parked vehicle unattended with the engine running or leave a vehicle engine running unnecessarily while that vehicle is stationary on a public road. Generally, if the vehicle is stationary and is likely to remain so for more than a couple of minutes, you should apply the parking brake and switch off the engine to reduce emissions and noise pollution. However it is permissible to leave the engine running if the vehicle is stationary in traffic or for diagnosing faults.

MUST NOT means that it's illegal.  Unfortunately the law in question [Section 98 of the The Road Vehicles (Construction and Use) Regulations 1986] actually says:

...the driver of a vehicle shall, when the vehicle is stationary, stop the action of any machinery attached to or forming part of the vehicle so far as may be necessary for the prevention of noise. (My emphasis.)

Nothing about not poisoning passers-by or trashing the environment with your toxic fumes.  Time it was updated methinks.

(Thumbs up emoji) Thanks!

Cars with stop-start usually have a higher-spec battery fitted, including circuitry that allows the ECU to monitor its condition and decide whether or not it can be relied upon to re-start the engine if the ECU stops it.

5) being complete arseholes and

6) deliberately messing up the environment and endangering other people.

CB

I posit Hanlon's Razor - "Never attribute to malice that which is adequately explained by stupidity"

A few years ago I pulled the ignition key off an unattended, idling van parked with doors open on my cycle path and threw it into the next meadow as far as I could.

I know I should not have done this*, but happy easter egg hunting, arseholes!

CB

* Of course I should have thrown it into the river instead.

I counter with CB's corollary: Living your stupidity out in public counts as malice.

CB

I'll grant that, although I try to be wary of throwing these around too much - it tends to be my own 'illusory superiority" manifesting itself....

Re: things it's not ok to do when you're in traffic, any sort of mobile device usage - these are the people who I loathe....

Because they are selfish, idiotic c—ts.

I’ve yet to receive a kind response when asking people to turn off idling cars.  Which I regularly do outside my workplace.  

As ever there appear to be nuances. This from Dr Felix Leach in the Guardian a while back:

"Of course, an idling vehicle will emit more CO2 and use more fuel than one that is switched off, but that is not the whole story. Other pollutants such as particulates, NOx, unburned fuel and carbon monoxide are carefully controlled on modern vehicles by filters and catalysts – and catalysts do not work when they are cold, and take some time to come up to temperature.

"The studies mentioned by PHE in its report advocating anti-idling do not consider most of these other pollutants, and there is a real risk of unintended harm, as emissions on start-up (whether warm or cold) often form a substantial part of the total emissions from a vehicle’s journey. A study from the US Department of Energy showed that a vehicle would have to be idling for 10 minutes or three hours to emit as much NOx or carbon monoxide (respectively) as a single (warm) restart. There is a significant need for more research in this area – particularly on modern vehicles that use substantial levels of exhaust gas after treatment to control emissions."

https://www.theguardian.com/environment/2019/mar/24/dieselgate-and-the-unin...

Filthy things, cars! So given the range of pollutants they chuck out, what is the optimum time after which we should turn our engines off?

With keyless, the engine will only start if you press the button IF your foot is on the brake (auto) or the clutch is down (manual) - if not, it just turns the electrics on. It's a safety feature that you can't start the engine by accident - usually applies to modern, key ignitions, too.

I read something about this recently - if your car is newer than 2015* you should turn off if it's going to be for more than 5 seconds, if your car is between 2015 and 2005* then you should do it if it's 30 seconds or more.

*dates are very approximate 'cos I can't remember them exactly, but the general gist is modern cars should be turned off sooner than older ones.

A few years back I did some work on developing variable valve timing for a couple of the big motor manufacturers. The sole purpose was to reduce emissions on start up. The idea was to retard the valve timing enough to reduce emissions, as you state the emissions on start up are a very significant part of the overall output.

The idea is simple enough, but to produce a reliable unit, cost effectively, is not. The unit cost target we were given was very low.

Despite making a couple of working prototypes, I have yet to see it applied.

Interesting thing was all the other ideas kicking about at the time that also reduced emissions considerably, which I have also yet to see in production.

In conclusion, switching off the engine is not as green as you think.

. 

I feel like I'm missing something in plain sight, how does it not being cost effective make it not as green as one thinks? Can't they be two different things, ie that which is cost effective and what the greenest thing to do is? 

This is probably why the auto engine cutout on my car is automatically disabled until the engine is warmed up a bit.

I think you have missed the point. 2 separate issues which you have somehow joined up.

Point 1 Car manufacturers are reluctant to pay out for emission improvements unless forced to (they are available just not cheap enough).

Point 2 Turning off the engine is not always the greenest thing to do (lots of ifs apply, but not nearly as simple as many think)

My "in conclusion" comment probably wasn't the best way of putting it, but it was referring to the simple idea that turning off the engine is better.

Hope that clarifies a bit.

A Mr Whippy ice cream van has recently taken to parking up outside my house in the  evening, engine idling. I wish they would turn the engine off. If they did, how long before the battery would go flat?

Its the cost bit. It doesnt matter how green the development is, its down to cost competitiveness in the vast majority of the car market.

This is an interesting video, seems the fuel argument is out the window https://www.youtube.com/watch?v=dFImHhNwbJo&t=13s

Old (and possibly new) ice cream vans use an engine driven compressor for the freezers, much like air conditioning

No mention of the emission spike when starting the engine though.

It would interesting to see the difference in emissions as the engine cools and where the break even point is, but I guess there are too many variables to play with.

Strange coincidence as this has been on my mind all day as it has come to a head.

I came home from work this morning to find my house smelled of diesel fumes-i had kept the window open and i live near a bus depot- i phoned up the council and told them do something and i wont let it go until they do, i also walked past a bus from said station belting out putrid black smoke. 
I see you can report "Smoky buses" but you need a reg num to do so,so i'll be waiting tomorrow to get it, im sick of this.
Also on my way to work I walk past an older guy every morning sitting in his white van reading The Sun with the engine on, im going to chap his window tomorrow and tell him to stop, ive been meaning to do it for ages.

Stick a note under his windscreen wiper and tap as you do, the hassle of getting out and reading it might cement the message a little bit?

I've found people just tell me I'm not a police man or what have you if I point out something they shouldn't be doing...

Edit: At least if he ignores you, he's had the hassle of getting out to read your note.

I think the starter motor in your car is probably designed to withstand a lot more use than that in a car without stop/start. If a car isn't designed for repeated stop/starts I would imagine that increasing the frequency of activating the starter in everyday driving will result in a shorter life for it.

7) it's an electric car, so the concept of idling is meaningless.

And also takes some time to cool down again...

Because once I’ve got the metherfecker to start, there is NO way I’m turning it off until I’ve got where I’m going. Then start the painful procedure again!

To do with the use of fuel, or the wear on the engine, or a combination - and in what sort of way? Pardon the many questions  I'm the son of an engineer, and mechanically minded (but not mathematically minded enough for engineering), and find this kind of thing interesting. 

Agreed. The quote I posted above mentions concerns over the amount of NOx and /or carbon monoxide emitted during a warm restart which in turn is presumably better than a cold restart.

Ok, my car has an option for automatic stop/start just like the New Nick B's. Do we keep the thing enabled and save on fuel and reduced CO2 emissions we would otherwise incur while idling (once the car has warmed up enough). Or do we switch the facility off to reduce the NOx, CO and particulates emissions spike when we start up again which in my experience will happen only a very small number of minutes after the motor cuts out? 

As drivers our direct interests are in saving fuel and less CO2 would be nice.

For the people we're driving past? They're probably more interested in minimising the other emissions, especially if our engines are less than optimally maintained.

What then should we be pressurising the manufacturers to do in the period of time before we're all driving electric cars (which will still have those carcinogenic particles rubbing off the tyres ....)? What's the algorithm for minimising all the nasties?

Not thinking. 

Learned in cars that didn't always start on the first go.

Stopped longer than planned, time just drifts by. 

Jk

youtube.com/watch?v=a_1OVYsLqMU&

Not entirely meaningless.  

Our EV has a load of something like 1 kW when turned on and going nowhere.  All the computers and sensors are fired up, bloody infotainment screen is on, the daylight running lights are on and I think the motor inverter is partially powered up.  

This translates to pollution and carbon emissions somewhere - although the idling EV is burning less energy than an ICE vehicle, the power generation is only about 40% fossil based, the power plants are cleaner and more efficient etc.

As the video linked to earlier in the thread shows, fuel consumption is lower, on stop/start driving.

However, also mentioned earlier, cooling of catalysts/engine etc come in to play as they work less efficiently, producing a spike in the emissions when starting. 

Lots of variables involved, i.e new cars designed to start stop will probably (like I would ever trust a motor manufacturer) account for it in the software.

Older cars put a squirt of extra fuel in, to get the engine to start, fuel injection does it better than carbs but it still does it. You may or may not remember manual chokes on carbs, and the fun they are.

You basically get a fuel rich mixture for a few seconds or longer depending on the engine/ ambient temperature on start up.

Older diesels are quite visible when starting as the fuel pumps give an extra shot of fuel resulting in a puff of black smoke on start up. Newer diesels save the cloud of smoke in a particulate filter DPF for disposal later when it gets hot enough, usually seen belching out the exhaust on the motorway. 

As I said earlier its not clear cut one way or the other. New cars that are (probably) designed to account for the emissions spike should be switched off. For older cars its not so clear where the break even point would be (if you ignore the fuel consumption).

Of course there would be less stop starts if the roads were designed better, making everyone more energy efficient, but road spending goes against the grain with many people.

Your car is designed to do this, on older cars it's not the same, stopping and starting, produce more smoke, puts a greater strain on the battery and associated equipment.

Obviously this doesn't mean we shouldn't be more aware and if you're going to be stood still for a while them switch it off.

Mine a f*cking nuisance because the radio goes off, so I have to switch it back on manually, then there's a massive gap after starting and it resuming the program I was listening too. Even worse if I have my Ipod connected, as it seems to want to read all the information on it before it starts playing; a little niggle in the scheme of things I know.

Worse than cars idling, is having to stop at traffic lights at might when there's little or no traffic, it must have a massive cost to the environment for no reason at all, turn them off during quite periods!!

If they are working properly, the particles are completely burnt to CO2 when the filter gets hot (unless you've been doing a lot of short journeys and get a warning that the filter is fully loaded).  

Now we Euro 6 diesels, which not only burn all the particulates but have low Nox emissions too.

That's what they are supposed to do, but I've lost count of the new vehicles I see with clouds of smoke coming out.