Cars engines that 'turn off' when in stationary traffic

Fitting suspension to a caravan ? ( did you ever get that to work)

Speed, – I’m just looking for the time the vehicle must be stationary to reach the ‘break even’ point where the cost of purchasing and maintaining the stop start system offers a genuine saving.

And just to add to the very original question – the ISG used in PSA diesels (a Valeo) unit is rated for 600,000 restarts. A quick calculation based on 50 re-starts a day (25 each way on the way to work/back which seems reasonable considering the logic which will sometimes disable the stop start system) gives a life of about 33 years if it was driven that way every single day of every year. Probably an acceptable service life.

I dont argue nettles. At least not whilst sober

Speed, – I’m just looking for the time the vehicle must be stationary to reach the ‘break even’ point where the cost of purchasing and maintaining the stop start system offers a genuine saving.

Sorry, you must have posted that just as I put my reply above in. That post probably provides an answer though in that basically you don’t have to worry about the wear and so it’s mainly just savings on running costs.

Thank you speed
And how much are they to replace ? – Part only

That should say fit – clearly you hopefully wont be replacing

I have to admit I’m not really sure about that. Certainly, and obviously, more than a ‘normal’ alternator but I honestly couldn’t say by how much.

Er should I not listen to the advice from the people who make the car? Engineers don’t know anything do they?

Engineers don’t run the car companies, accountants do. 💡

Engineers don’t run the car companies, accountants do

Yes, but not as much as most people think. The majority of the OEMs I’ve worked with are pretty sensible when it comes to listening to the engineers and speccing the correct components.

One point to note, if the oil is fully synthetic, then the some of the [important to old engines] hydrocarbon chains have been removed through sever hydroprocessing this can effect seals and potentially cause leaks.

You’d have to be looking at some pretty old metal for this to be a problem, it’s certainly no issue on my MkII Micra, which is just stepping into adulthood. 😀

ericemel – Member

Unsure – but I am getting 48mpg generally in town traffic in a car that does 0-60 in 7sec. I am not grumbling!

Out of interest, is that calculated or from the trip computer?

I ask as according to the trip computer on my M5, I was achieving over 25mpg, whereas according to the number of miles I was doing relative to the amount of fuel I was putting in, I was getting 16-19mpg.

Similarly, my mates motor does almost 60mpg, apparantly, while my Micra achieves only low 50s. Strange that my Micra needs less fuel to complete the same journey then…

Speed, – I’m just looking for the time the vehicle must be stationary to reach the ‘break even’ point where the cost of purchasing and maintaining the stop start system offers a genuine saving

The idea of a Stop Start system isn’t to save fuel from a Customers point, it is to fulfil the manufacturers obligation to reduce cO2, obviously through their vigorous testing & calculations they can prove a cO2 reduction on the car, thus reducing emissions, this is sold on to the end user as a benefit, but in reality isn’t really!

this is sold on to the end user as a benefit, but in reality isn’t really!

Well, it is still a benefit (engine off = no fuel being used = fuel saving), but your right it is tailored a bit to the emissions cycle. Although having said that, the idle periods in the NEDC or any other cycle are probably the only bits that directly imitate something that happens in real driving so any benefits you see on an emissions test in the idle sections will certainly be seen in real life as well.

Mol – You should listen, just not believe by default.

From the man who’s default is to argue, not listen

Hehe.. Don’t argue and listen, or don’t accept whatever I’m told – make your minds up!

Re saving fuel – it clearly will save fuel – how much depends on your driving, like I say. Many people spend a lot of time stopped in traffic. Although, in traffic I seem to spend a long time creeping forwards, which is why I like my hybrid.

And just to add to the very original question – the ISG used in PSA diesels (a Valeo) unit is rated for 600,000 restarts.

A very high quality answer to the OP 🙂

i work for a major automotive oem. one of my components interacts with the stop start system. funnily enough the duty cycle of the starter and the battery and so on is considered. very much so!

re savings – the published c02 figures are only achievable with SS switched on

If the engineers were in charge, vehicles would not be built to have such short lives, but then the car manufacturers would all go out of business fairly quickly.

There were vehicles built like this – the original electric milk floats were built incredibly strong (they did have to carry an enormous set of heavy batteries) and consequently lasted for, in many cases, decades. Unfortunately the manufacturers generally didn’t: with no sales pipeline of replacements, once the urban dairies that had a use for the things all had their fleets, the order books dried up and that was that.

vehicles would not be built to have such short lives

They aren’t.

Remember when 90k miles used to be a lot?

“Remember when 90k miles used to be a lot? “

no ….. my dads 87 audi 80 was on 240k when he traded it in.

my LR 90 did 180k on its original engine and the 1990s engine that replaced it is on 160k!

Older than that.

My mate’s 52 Octavia is on 200k.

Got any real evidence for the decreased longevity of cars? That is not coloured by the low value of high mileage cars meaning people won’t shell out for them to be fixed even though they could?

Even then, there does seem to be this myth that modern cars need to have parts replaced as standard after a year or two which is quite frankly rubbish. OK, if one of the more complex system goes then it goes quite badly, but on the other hand if it doesn’t go then there is no reason why it would within the reasonable lifetime of the part/vehicle. I’ve seen test engines running in utterly horrific test sequences (full load from cold, cold flash soaks, high load low revs, etc) for the equivalent of about 500k and still working fine on original components!

Well the big hurdel with stop start is enine bearing wear. Starting with low preasure, think new bearing material is being used.

Electric cars, potentialy good but the way the power is generated has to be resolved. Hydrogen looks to be the future but thats a long way off.

Power generating isn’t so much of an issue with electrics, storage is.

using petrol to generate the electicity in the car itself would be a viable stepping stone. Run a petrol/diesel where it is most efficient, then use electric motors to produce the drive. Keeps the big guys using all the I/C tech and allows development of batteries and motors. This solves the problem of storage as most of the energy needed for an entire journey is stored in the petrol/diesel, and only converted to electrical energy when (or shortly before) its needed.

Prius is an inefficient dinosaur, only benefit is that it does not emit H/Cs in already polluted urban/city environments which is why it took off in places like L.A and gets the congestion break in London. Plenty of more efficient conventional cars.

As for Passats and electronic handbrake; used one on my advanced driving course and the worst, most frustating car I drove. The parking brake is as another poster said a solution looking for a problem, unbelievably noisy mechanism and the car is awful to drive in full auto. Having not driven an auto box for years I assumed they’d improved but the throttle response was downright dangerous when trying to drive it ‘properly’. Much better in semi-auto but a frustrating driving experience.

http://en.wikipedia.org/wiki/Toyota_Prius#Fuel_economy_and_emissions

http://singletrackworld.com/forum/topic/that-electric-car-on-top-gear-last-night

using petrol to generate the electicity in the car itself would be a viable stepping stone. Run a petrol/diesel where it is most efficient, then use electric motors to produce the drive

You mean the Vauxhall Ampera?

Prius is an inefficient dinosaur, only benefit is that it does not emit H/Cs in already polluted urban/city environments which is why it took off in places like L.A

Well no, the reason it took off in the USA is because they ahve really strict NOx emission laws, and diesels failed those for many years. VW only got around it by adding a NOx scrubber to the exhaust which is very expensive, and tha tonly came out in 2010 or something recent. Prius will get you 70mpg with lower CO2 and far lower NOx than a diesel. So it’s not really an ‘inefficent dinosaur’.

I’d love an Ampera however they cost a bomb.

the throttle response was downright dangerous when trying to drive it ‘properly’

Nah, you’re just not used to it. They are very popular amongst boy racer GTI owners too so it’s not just me.

Got any real evidence for the decreased longevity of cars? That is not coloured by the low value of high mileage cars meaning people won’t shell out for them to be fixed even though they could? [/quote[

Surely the cost of repair vs value of car is the sole reason for scrapping? Ignoring it is meaningless. Who’s going to bother repairing an aging diesel when the injectors, DPF, Dual Mass Flywheel etc. needs replacing?

Nothing to do with OP, but my 03 Ibiza is on 202k miles….original clutch, exhaust, dual mass flywheel, turbo, battery…
And I gave up on the 10k service intervals at about 115k miles. I now get it serviced every 15k miles.
Front discs & pads were first replaced at 119k miles so hoping to get to 240k on this set.

Not exactly disposable…

Oh, and I even turn the engine off at level crossings.

I’d love an Ampera however they cost a bomb

So it’s not really an ‘inefficent dinosaur’.

I mean inefficient in terms of the technology it uses, not compared to the average car on the road now. If toyota started from scratch now it would be far more efficient, both in terms of battery type and engine use. The Ampera might cost a bomb but most new tech does. Not bashing the Prius if that’s how it sounded, but as the first of its kind (mass market) the engine, motors and batteries are all old technology.

Prius highway mileage is closer to 50mpg than 70 and plenty of petrol (not diesel) cars do that- all the new lower capacity turbo petrols are making diesels look like anachronisms.

They are very popular amongst boy racer GTI owners too so it’s not just me.

poor trolling. 3/10. Police advanced driver, used a variety of powerful saloons from numerous manufacturers on a surveillance team, and the auto box can’t be driven properly. Try driving through a bend on positive throttle you get no response,no response,no response,no response, box kicks down a gear and car accelerates abruptly (talking about full auto mode, semi auto a totally different kettle of fish).

I mean inefficient in terms of the technology it uses, not compared to the average car on the road now. If toyota started from scratch now it would be far more efficient, both in terms of battery type and engine use

Hmm, it’s not bad for what it is. The engine is still pretty clever although it should be direct injection I think. However the extra fuel wasted by throttling a non DI engine is not wasted in the Prius so maybe it’s less of an issue.

The reason the battery is old tech is because it’s cheaper, and the parallel hybrid design only requires a small battery, which is why the car’s cheaper, and also how come the battery’s designed to last the life of the car. The parallel hybrid is just a petrol car made more efficient, the Ampera is an electric car with petrol backup.

Prius highway mileage is closer to 50mpg than 70 and plenty of petrol (not diesel) cars do that- all the new lower capacity turbo petrols are making diesels look like anachronisms

No it’s not – I’ve driven 90k miles in a MkII, and the new ones are better. Are you comparing poor real world stats with manufacturer’s test figures for turbo petrols? Everyone I’ve asked about VAG 1.2 TSIs cna’t get more than 40 or so.

Try driving through a bend on positive throttle you get no response,no response,no response,no response, box kicks down a gear and car accelerates abruptly

So your point is that it’s not like driving a manual? Of course not. That’s why they still sell manuals. And in any case there is a way around that situation you describe.. but then again I’m used to it so I know 🙂 And by the way, there’s no such thing as “proper” driving.

Well there is, but it’s appropriate driving for the conditions, whatever they are. So cruising smoothly on a motorway and driving nice and gently is usually proper driving*, and the DSG is ace at that.

It’s a good system, it’s not everyone’s cup of tea but it’s still a good system. And if you really want to be an advanced police driver then it has flappy paddles for your corner-holding throttle situation.

* unless you are chasing criminals which, let’s be honest, not many of us do.

SO you save 1p worth of fuel for 30secs stationary at each set of lights on your drive in to work.
Save more by not driving like a twunt , reading the road ahead, correctly inflating and checking tyres and tracking.
You have to accelerate the mass of the bigger battery , and bigger starter motor , plus the electronics required up to speed each traffic light . I know its not huge but bigger = heavier ( mostly )

More to go wrong if the system fails, more expensive to produce. More to recylcle at end of life

my BMW 320D has it and it’s the first thing I switch off when I get in. Having done 27K in six months and having spent £800 on two services and £500 on tyres I won’t have the car long enough to see if it will fail! It does achieve very good MPG and has 185bhp with £30 tax so can’t complain too much

Save more by not driving like a twunt , reading the road ahead, correctly inflating and checking tyres and tracking.

Yeah but you can do those things AS WELL as using start-stop. Not seeing the problem here. You do waste fuel when idling it’s not a myth.

More to recylcle at end of life

Hardly, it’s only a bit larger.

Company fuel cards will waste more fuel than ‘Start Stop’ will ever save.
As would an enforced 60mph motorway speed limit.

Company fuel cards will waste more fuel than ‘Start Stop’ will ever save.

How do you work that out ?

As would an enforced 60mph motorway speed limit

It would be a start if 70mph was enforced

As would an enforced 60mph motorway speed limit.

You clearly don’t use them…… Try diong 60MPH around the M60 or M62, you’d be over the moon to reach 60!

My car is worse on fuel at 60 than it is at 80, it’s been geared specifically for motorway use

My car is worse on fuel at 60 than it is at 80, it’s been geared specifically for motorway use

hhhmmmm , engine spins faster = more bangs per second. sceptical man is sceptical . i think this not to be possible ( real speed not indicated on your speedos)

Drag increases with speed , hmmmmm

and i use the motorway every day thanksssss .

geordiemick00 – which car? I’ve yet to use a car that’s more fuel efficient at 80 then 60mph (many of them designed with motorway cruising in mind).

hhhmmmm , engine spins faster = more bangs per second. sceptical man is sceptical . i think this not to be possible ( real speed not indicated on your speedos)

Drag increases with speed , hmmmmm

and i use the motorway every day thanksssss .

In an ideal world then yes, as the engine spins faster it would require more fuel to keep it spinning. But this isn’t an ideal world and the fuelling curve as the engine speed increases is not linear by any stretch of the imagination. There is a band in pretty much any engine where the fuelling will decrease (or at least stay level) as the speed rises, before increasing again. This depends on the combustion design, bearing and general friction/lubrication design as well as the efficiency of the intake system and…well…a lot of things!

Drag does increase with speed (by its square in fact), but depending on the vehicle aero and the engine efficiency, tyre rolling resistance etc, it is very definitely possible to be more economical at 80mph than at 60mph.

(doesn’t mean most cars are…but it is certainly possible!)

I’d love to see some info to prove it, but I am yet to drive a car that is more economical at 80mph, than 60mph……unless being driven in the wrong gear, perhaps.

Drag alone must mean that any ‘gearing’ or mapping efficiency improvements would be completely outdone.

Drag increases as the square of speed, so
For simplicity…..
60mph = 3 units…..3^2 = 9
80mph = 4 units…..4^2 = 16

or 65% more units of drag…..

I know in my Ibiza (1.9TDi 130) that 80mph equates to about 2200 rpm and I can get a max of about 53mpg out of it.
At 60mph (1500rpm or thereabouts), I can easily get >60mpg, with a highest of around 64mpg.

The 60mph economy value is based on tank to tank fills, whereas the 80mph economy value is from the trip computer, so actual is probably a bit lower.