Do 'stop start' cars save money?

sevenhills

I drive a VW Crafter that has stop-start techknowledgy. Sometimes the icon comes up on the dashboard and it just carries on ticking over. Sometimes it switches off when I am not expecting it, because I often turn it off.

Sometimes it tells me to start the engine with the key, it's just a pain.

I cannot believe it saves any money, when you take into account it may need a new start motor earlier.

I sometimes switch the engine off with the key, when I am sure I will be stood for a while.

Is that legal, is it ok to sit at the traffic lights with the ignition off, waiting to start the engine. Will the glow plugs or coil overheat?

Bonniepurple

Mine is completely random.  Pausing at a junction - it kicks in.  Waiting for slow traffic lights to change-nope.  I think it is a complete gimmick.

stuhse

To answer your question you need to consider whether your engine uses more or less fuel when it switched on compared to when it is switched off.  Regarding wear to starter motor, my stop start car is 5 years old with 104000 miles and hasn't needed a replacement starter motor .

forgotmyname

Works better on some cars compared to others. Only helps if you do the type of journeys where it will switch
the engine off. Family members journey is short enough where the parameters are not met for the stop
start to kick in.

I took them to work one day and then took it to the MOT for them and it was a PITA, just about to pull out onto
a busy road with limited gaps and it cuts out. Luckily I was quick enough to abort pulling out.

The stop start system really should not have thought that was the correct time to cut the engine.

Bigwheels1111

I have it on my Peugeot 5008 auto.
When and if it worked it was very good.
I could not move my foot from brake to accelerator before it had started seamlessly.
No hesitation.
But it very rarely works, now I have a tracker for insurance it never work.
So alls good.

jimbo6977

Have it on a Skoda Octavia and it's etech so also has coasting/sailing mode which switches the engine off while moving (a battery powers the brake and steering assistance). Whether it "works" depends on some factors like whether the aircon needs a lot of power at a given moment, but the main determining factor seems to be driving style. 

SiliconChip

I seem to recall a thread here some years ago where it was suggested that the engine needs to be stopped for at least 8 seconds for the cost of restarting to be offset by the saving in fuel not used, although I'm not sure where that number came from. I found that my car restarted in under that time on the majority of occasions, although the times when it was stopped for significantly longer may have led to an overall saving.

However, as others are saying, it rarely works at all these days so the point is moot anyway, although if I see that I'm going to be stopped for a long period I'll usually turn the engine off manually.

WellKnownSid

On the basis that every car I’ve owned pre stop/start needed a new battery, or starter or alternator at some point - but none of the five cars I’ve owned with stop/start since have suggests a lower cost of ownership due to better engineering.

The one exception was my 1600L Ford Cortina estate. This developed a stop/start capability at around ten years old and I ended up replacing most of the parts on that car.

Stubod

..it's a gimmick to maximise a cars published fuel consumption figures during the mandatory manufacturers "official fuel consumption" test....nothing more nothing less....

sevenhills

SiliconChip said:

However, as others are saying, it rarely works at all these days so the point is moot anyway, although if I see that I'm going to be stopped for a long period I'll usually turn the engine off manually.

But why doesn't it work?

If the battery is low it doesn't work and if you are drawing electricity from the battery, but it doesn't work when the blower is off, I only have the radio and front DRL on.

abc.xyz

Hasn't worked on my car for years. Can't say I noticed any fuel efficiency when it did work, and it did it so infrequently I'd always think I'd stalled