Do you have start stop system turned off?

Soldato
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Not at all. I'm suggesting that in the real world there might be increased fuel consumption due to the constant engine restarting. The test also doesn't look at what happens a few years later when the engine is older and worn. Where are the long term studies over the lifetime of the vehicle on emissions of fuel and (possible) additional maintenance?

We shouldn't just assume that because a car was tested in a relatively controlled way before it is sold, that it represents the real world over 10 or 15 years.

Happy to be corrected of there are some reliable lifetime studies which have been done.

https://www.youtube.com/watch?v=dFImHhNwbJo

You'd be surprised how much fuel it can save. It's not just for "emissions".

This answers the question regarding how much extra fuel is needed to start the engine as opposed to just letting it idle.
tl;dw? The amount of fuel required to start the engine was equal to the amount of fuel required to idle for approximately 7 seconds. So if you're sat for any longer than that, then shutting down the engine should save fuel.

As for long term wear and tear...well, it's a concern, but I doubt very much it's not one that's been factored in by engineers. Also consider that there are some stop/start systems which don't require the starter motor (so no extra wear on that, or the battery), and these systems also don't activate until the engine is up to temperature, so there's no worries about increased wear due to repeated cold starts.

EDIT: and as Fox pointed out, there's also the benefit that it's more pleasant to have the engine shut off when sat for long periods; not just for the driver, but in urban areas, for pedestrians too.
 
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Increased hybridisation means theres less metal to metal type restarts. My Discovery Sport with the 48V MHEV is far far smoother than the Velar was with a starter, even more pronounced as diesel high cranking torque and shake through cabin.

48V so will regen on braking anyway so its not even like you need to find extra energy.

Its frankly a no brainer in terms of effect on NEDC and WLTP, let alone real world including the reduction in noise of cars idling in traffic.
 
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Soldato
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Can't remember if I've posted before but I did have mine enabled for quite a while but found it annoying, especially when entering a roundabout, it sometimes stopped the engine which caused a few worrying moments. I've since coded mine to be off by default so I have to manually enable it except in Eco mode where it defaults to enabled.

I watched the CarWow review of the new 440i and that has a system that I would use, battery powered initial launch with the engine kicking in a few seconds later.
 
Soldato
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Well having tried it on both our cars you definitely use less fuel if you let it so it's thing.
Are the people saying it is no good the same people that think a car that's done 100k is scrap.

My friend that does starters and batteries tells me there more reliable than standard parts, starters designed to massively out perform standard ones in both power and life.
Battery systems in cars that look after the battery, though a lot of places when changing a battery don't bother resetting the BMS and this can lead to issues as the car still thinks it has an old battery fitted.

The Mazda system is perfect, stops the engine with a piston at full compression, then when you want to start injects the fuel and ignites it, no starter involved.
 
Soldato
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Yes - because it's pointless. It's only function is to make the official fuel consumption figures look better. The car manufacturers know how the test is run and developed stop-start for precisely that reason.

Yes, I agree. They've made the fuel consumption figures look better by reducing the fuel consumption. The bounders!
 
Soldato
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Yes - because it's pointless. It's only function is to make the official fuel consumption figures look better. The car manufacturers know how the test is run and developed stop-start for precisely that reason.
It reduced fuel consumption, correct - so has a purpose (as has been covered already).
 
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The wife's Tiguan has stop/start. Most of the time it's pretty intelligent so I let it do its thing, but if I know I'm going to have to pull away swiftly I'll just keep the car in gear with the clutch down and it won't cut the engine.

Since it's been mentioned, I find the hill start assist very useful too, until I get back in my car! I had it on a works Transit Jumbo too, Godsend.
 
Soldato
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Turn it off straight away when I get in the car, I find with the DSG its a little eager turning the engine off. I will enable it if I am stuck in traffic.
 
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