... turn it off?
Ref: BMW/VAG.
Really dont like the idea.
And what happens if you are sitting in a queue and it is -5deg or 30deg and you dont want to freeze / swelter, does the system recognise that it needs the engine and start it to produce heat / aircon?
Any knowledge / experiences?
Thanks.
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Well I was wondering how it would work in a learner drivers car because if id come to a stop and the engine went off, id most likely have failed by the end of the test!
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I had a BMW with this system, as a hire car for one day. No briefing about it on pick up so something of a panic at the first traffic lights! I didn't like it in the short term and I don't think I would get used to it in the long term. I didn't read the handbook (in German in Germany!) so I can't answer Cheddar's points.
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... and in terms of TOTAL environmental impact there must be plenty of negatives!
FTF
Edited by fredthefifth on 27/09/2009 at 11:28
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For years we were all told that the cruellest thing you could do an engine was to subject it to stop/start usage. So we'd try to avoid short journeys, and if we stopped we'd leave the engine running for a minute or two rather than subject it to a another start up when the oil has drained back to the sump.
And now who's making our cars do this stop/start stuff on their own, even if we don't ask them to? Yup, it's the people who will sell us the new engines we'll need when the stop-start.
As FTF says, the total environmental impact isn't pretty. But if it pushes down the Co2 figure in the crummy CO2 test, then never mind the bigger picture, eh?
Edited by NowWheels on 27/09/2009 at 11:57
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But can you turn if off?
If so no problem.
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And I suppose that if its bad for wear and tear, then in the long term the agencies involved in looking afer cars, servicing, parts etc will gain!
If it can be switched off then I doubt that the CO2 figure would be adjusted.
FTF
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I doubt that Stop / Start is accounted for in measuring CO2.
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The fuel consumption/CO2 test specifically excludes stop/start-it is driven to a set drive cycle and must idle between sections.As it must do on the emission test(same cycle but emission is cold start-CO2 hot start).
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The fuel consumption/CO2 test specifically excludes stop/start
From a What Car news report:
"Ford's new Focus Econetic will be the company's first model to feature stop-start technology when it goes on sale in 2010, bringing CO2 emissions down to just 99g/km."
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Am I not right in thinking starting a petrol engine requires a small amount on enrichment?
im thinking back to carbs where a small amount of throttle aided starting.. if so will stop/start INCREASE fuel consumption in some cases?
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The system will only 'stop/start' if the engine is warm and the draw on the battery/alternator is less than a certain limit. So, it will work even on the EU test assuming the engine has reached the appropriate operating temp.
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A/C demand will keep the engine running (certainly with BMW).
I think it's a great technology, it's daft keeping an engine thrashing away for nothing.
There is no enrichment on a hot start. It is not restarting with a conventional starter motor, the generator/starter is part of the engine assembly and is used for regenerative engine braking too.
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The question was asked in HJ's column in August - tinyurl.com/y8bas7v
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The official figures quoted will not include stop/start-it can be mentioned but it does not make it an "official" figure.
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The official figures quoted will not include stop/start-it can be mentioned but it does not make it an "official" figure.
What makes you think that? Seems an odd thing to say, the system would be totally pointless if it wasn't used in the tests.
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What makes me think it?;our office was responsible for the figures!!!!!!!!!!!!!!!!!!!!.I agree pointless but nevertheless it's the regulation(law).
Edited by jc2 on 27/09/2009 at 18:54
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I agree pointless but nevertheless it's the regulation(law).
So a car with stop/start that couldn't be disabled wouldn't be able to publish official figures?
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On the Honda IMA you can, effectively, turn it off by keeping the air-con on. Irritating in the extreme, especially with such a quiet engine.
Edited by Pugugly on 27/09/2009 at 19:35
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YES it can be switched off if needed - there's an override button.
Driving style is a big factor - i.e. it will only cut in when you put it into neutral and release the clutch (in a manual car) and put the handbrake on. Generally people only do that if they expect to be stationary (e.g. at red lights) for a minute or so. If you just stop briefly (e.g. at a junction), you wouldn't put the handbrake on so the system wouldn't engage.
jc2 is wrong - the benefit **is** included in the official co2 tests and mpg figures. Do you really think the manufacturers would bother fitting it if it had no measurable mpg or co/2 benefit! Manufacturers aren't allowed to quote "unofficial" co/2 or mpg figures. There's plenty of evidence - numerous manufacturers have introduced it on existing models with no other modifications and the published co/2 and fuel consumption figures improve accordingly (up to around 7% ish).
Example www.landrover.co.uk/gb/en/vehicles/freelander-2/In...m (sorry - don't know how to tinyURL)
System works best in congested town driving (can be as much as a 10% fuel consumption benefit).
It does take engine demand into account - it won't cut a cold engine, or if heater is needed, or if battery is low etc etc. Latest generation design uses electric motor air con compressor and electric engine coolant pumps so once the engine is warmed up, you're no so reliant on the engine being running in order to get hot/cold air. These systems rely heavily on regenerating alternators which put big current back into the battery on the overrun (i.e. during engine braking) which has the incidental benefit of reduced brake wear.
A common concern people usually have is regarding turbo damage - i.e. cutting engine oil circulation before turbo spindown/heat dissipation - but ECU takes that into account and won't cut engine if risk of damage.
Can sometimes be defeated in a manual gearbox car. The "signal" to restart the engine is the clutch being dipped and if you're quick you can end up trying to pull away before the engine has chance to fire (but you really have to be trying deliberately for that to happen).
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Not quite;to publish the official figures,the tests must be run without stop/start.You could sell a car with stop/start working 100% but the official figures quoted must have been run with it disabled(and the same for the emission tests).How you would then carry out production conformity tests(another legal requirement)is something else.
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Can you tell me of a car where it cannot be disabled please??.This technology is nothing new;it first appeared in the 70's.
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Volkswagen Golf Umwelt (?) circa 198 something.
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Looking at some of the CO 2 figures for Audi's with stop-start shows it has made a difference. It makes a big difference for the BIK figures for company car drivers. I'd certainly look at some of these - indeed some petrol turbos become cheaper for BIK than some diesels.
I'd probably want to turn it off if I found I didn't like it though but the car would have the lower recognised CO 2 figure.
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Looking at some of the CO 2 figures for Audi's with stop-start shows it has made a difference. It makes a big difference for the BIK figures for company car drivers.>>
I dont think that is the case, it is other changes made at the same time that have improved the CO2 output. I cant see how stop start can improve official CO2 unless it includes a significant proportion of the time allowed sitting at standstill.
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The amount of time at idle in the legal test is low;the engine would not switch off immediately at idle and would restart as soon as you put the clutch down to re-engage gear both reducing this time to even less.
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Can you tell me of a car where it cannot be disabled please??.This technology is nothing new;it first appeared in the 70's.
I think it first appeared in the 30's and was called Startex.....according to my father who told me about such a system when he was alive, at least that what he remembered it being called.
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As FTF says the total environmental impact isn't pretty.
What is the "total environmental impact" of this, then?
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>> As FTF says the total environmental impact isn't pretty. What is the "total environmental impact" of this then?
So it's not pretty, but the actual impact is unknown? Is that it?
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I'm not sure about BMW or VAG but Volvo have just added stop/start to the C30 which reduces the CO2 to 104g/km from 119 I think it was.
This car now has a second battery fitted low down at the front of the car so it cannot be bought with the R-Design body kit. This is for aircon/heater systems so you don't freeze or swelter.
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As per my comment above Stop / Start alone cannot reduce CO2 that much.
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My problem is that I want to be in control, I dont want my car to turn itself off or start itself, I want to decide.
I am sensible enough not to leave it idling for hours in a tail back, this is another Big Brother move IMO.
Now if it looks like a 4 cyl diesel BMW or VAG is on the cards then I dont think they will get my business unless I can turn the Stop / Start off.
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I used to have an R reg whose engine stopped at junctions.Unfortunately it had a faulty Idle control valve so it couldn't really be classed as a stop/start!!.
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>>I want to decide.
Generally, you're better leaving this to the car to work out. Most people will get it wrong. To save fuel, the engine only needs to be stopped for seconds!
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Now if it looks like a 4 cyl diesel BMW or VAG is on the cards then I dont think they will get my business unless I can turn the Stop / Start off.
Every single review to these cars I've seen mentions the ability to turn it off.
However, I'd buy a 6 pot BMW without stop/start to be on the safe side... ;)
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Every single review to these cars I've seen mentions the ability to turn it off.
Really, a switch rather than fooling it via aircon etc?
However I'd buy a 6 pot BMW without stop/start to be on the safe side... ;)
>>
Hmmmm, (scratches chin)
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Cheddar you know you want one.
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To be honest PU, as I have said eslewhere I am being tempted back into employment after a few years of being self-employed, I have a very attractive offer though dont have details of the car scheme other that a company car is offered. I dont yet know whether an allowance is an option or the budget / lease values etc however I really doubt it would stretch to a well speced 320d yet alone a 6cyl one, should get the details shortly now.
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Well I know I want one ! I have word of a low mileage immaculate 325 petrol ( three years old) - if it matches my expectations I may buy it. It is a seriously nice low profile well specced (think nice little fairy lights on the door handles) one - owner may be looking to sell to buy an X1.......
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Really a switch rather than fooling it via aircon etc?
I admit I haven't tried one myself, but online owner reviews have mentioned that it needs to be turned off every trip.
So it seems pretty certain, that yes you can turn it off, but it sounds like it's a software function, rather than a simple button on the dash that you can leave switched on or off.
Not ideal, but at least it can be switched off!
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It will be interesting when all the foretold hybrids hit the market. The Prius doesn't give you the option, but I don't know whether their official fugures have the engine stop when forward motion ceases or not. Out of interest, I formally enquired of our Land Transport mob as to how they test hybrids. Apparently, the Prius computer can be "adjusted" to keep the engine running for test purposes, but Toyota allow only their trained techies to have the computer entry password.
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The Honda insight I owned for 9 years used it's IMA system to spin up the engine....I would be wary of systems that used the conventional starter system to perform this task.
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>>I would be wary of systems that used the conventional starter system to perform this task.
I don't see any reason to be wary - it's not as if starters are delicate parts prone to failure.
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Was following a MINI with this in crawling traffic on the M6 last friday night. Was very irritating having to wait while the thing fired up before they could move in the queue. You could tell by the rear lights dimming while the starter was engaged.
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There really is nothing new, is there? I had a B reg Jetta Formel E with a switchable engine cut-out. The starter span when you engaged first gear.
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What is the answer to Cheddar's question?
Can you, or can you not, turn the stuttering thing off?
Too late; I have already decided, I don't want one of the things.
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"Was very irritating having to wait while the thing fired up before they could move in the queue."
Must have been the driver being slow. Dip the clutch and it starts straight away, with no delay.
For some reason, start/stop isn't working on SWMBO's new Mini convertible: she doesn't like start/stop so we won't do anything about it. It may be that she's got the air conditioning on with the roof down - which would probably disable start/stop anyway.
Edited by Avant on 30/09/2009 at 00:19
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