Do 'stop start' cars save money?

NBLondon

My 2011 Focus has it.  It hasn't kicked in for years - presumably because when I'm in stop-start traffic I usually have the aircon switched on.  Never really noticed any difference.

chrisw

Herzlos said:

forgotmyname said:

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.

Stop start should only kick in when you're in neutral with your foot off the clutch, so I can't figure out why it'd turn the car off when you're just about to pull away from a junction unless you're doing something strange or it's broken.

That's fine in a manual but an automatic doesn't know you'll want to pull away in a couple of seconds. As you slow to a stop and immediately start to pull away, it feels like the engine and gearbox are falling over themselves to get into the right position. 

So my routine is seatbelt on, engine on, s/s off.

motorguy

chrisw said:

Herzlos said:

forgotmyname said:

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.

Stop start should only kick in when you're in neutral with your foot off the clutch, so I can't figure out why it'd turn the car off when you're just about to pull away from a junction unless you're doing something strange or it's broken.

That's fine in a manual but an automatic doesn't know you'll want to pull away in a couple of seconds. As you slow to a stop and immediately start to pull away, it feels like the engine and gearbox are falling over themselves to get into the right position. 

So my routine is seatbelt on, engine on, s/s off.

i guess it depends on the auto.  Any recent autos we've had it doesnt do it unless you've your foot on the brake and the car has come to a stop.  It instantly starts up when you take your foot off the brake to move to the accelerator.

tedted

one of my daughters has a stop start auto car and loves it,drive up to traffic lights and foot on  brake engine stops foot off and she is away straight away and her car has the alternator system where it does the charging and starting

sevenhills

I just listened to a video from VW and it talked about the temperature of the engine, I would have thought the condition of the battery to be the deciding factor.

I think that would be the issue with mine, but the battery has never let me down. I should get my multimeter and check its voltage.

WellKnownSid

chrisw said:

That's fine in a manual but an automatic doesn't know you'll want to pull away in a couple of seconds. As you slow to a stop and immediately start to pull away, it feels like the engine and gearbox are falling over themselves to get into the right position. 

So my routine is seatbelt on, engine on, s/s off.

My wife's 12 year old auto with s/s works fine.  Never seems to stumble, no matter how soon you want to pull away it always pulls away immediately and smoothly.  Probably down to the design.

Username03725

So my routine is seatbelt on, engine on, s/s off.

That’s a shame, routinely switching it out for presumably one specific part of a regular route. Mine gets turned on & off to suit in busy traffic but it’s the same as wipers, main beam & fog lights etc - on or off as required on a journey.

sevenhills said:

I just listened to a video from VW and it talked about the temperature of the engine, I would have thought the condition of the battery to be the deciding factor..

As per earlier post, battery state, current electrical load, engine temp, external temp; all are taken into account by the engine management.

ontheroad1970

Herzlos said:

forgotmyname said:

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.

Stop start should only kick in when you're in neutral with your foot off the clutch, so I can't figure out why it'd turn the car off when you're just about to pull away from a junction unless you're doing something strange or it's broken.


Normally it'll have the engine back on before you're even close to taking off from a complete stop.

My last 2 cars have had it, and whilst initially I'd disable it there's really no point.
It only really kicks in in the kind of heavy traffic where you're not moving for a while. It'd seem like a nightmare if you're the sort of driver to roll forward 2ft every time you can instead of allowing a small gap to appear.
My last one tends to turn the engine back on after 45 seconds.

On an auto, it will kick in when your foot is hard on the brake pedal.  Take your weight off the pedal (even with the brake still on) and the engine fires up immediately

Goudy

My car usually tells me why the stop start has been suspended.
Like "optimising cabin temp" or "optimising battery charge" and it's correct, it was introduced to save C02 and if it's doing that it must save some fuel.

A while ago I had a Citroen HDi Airdream and that used to collect energy from the last bit of braking (last 10 feet or so it would stall), store it in some capacitors and use that to start via the alternator, so didn't restart with the starter motor or power from the battery.

It was the best stop start system I have ever come across.
Smooth, instant and worked every time, even soon after a cold start.

My auto Clio's stop start is ok, if the auto handbrake is on it does take a prod of the accelerator to restart but if it's off it fires up pretty quickly once you let some pressure off the brake pedal.
It tends to work better on my way to work in the mornings rather than on my way home later in the day, can't figure out why though.

Robbo66

Stop start is a con to get a lower emissions score, whether it actually does reduce emissions is anyones guess. Mine spend more time not working than actually working.