Auto start/stop
Discussion
Pretty much all new cars seem to come with this function for all the usual (utterly stupid) emissions reasons, what are people's experiences of it? A few qs from me:-
(1) Does it operate even while the engine is warming up? If it does, is it not giving you lots of little cold starts? Surely this is not great for the engine. (I have almost no technical knowledge at all.)
(2) If it is a good idea to switch off the engine at lights, etc, why do all the guides say to switch off the engine if you are sitting for 3 mins or more? Why not say "Switch off your engine if likely to be still for more than a few seconds)?
(3) Is it right that engines are actually fairly unhappy (i.e. suffering more wear than usual) at idle? If so, see question (2) above.
Perhaps this is all on a wrong premise and the operation of the start/stop function is not the same as switching the engine off and on in a car that does not have the function. The few times I have driven a start/stop car (or been a passenger in one), it didnt seem to be as dramatic as would be starting and stopping a car without the function.
(1) Does it operate even while the engine is warming up? If it does, is it not giving you lots of little cold starts? Surely this is not great for the engine. (I have almost no technical knowledge at all.)
(2) If it is a good idea to switch off the engine at lights, etc, why do all the guides say to switch off the engine if you are sitting for 3 mins or more? Why not say "Switch off your engine if likely to be still for more than a few seconds)?
(3) Is it right that engines are actually fairly unhappy (i.e. suffering more wear than usual) at idle? If so, see question (2) above.
Perhaps this is all on a wrong premise and the operation of the start/stop function is not the same as switching the engine off and on in a car that does not have the function. The few times I have driven a start/stop car (or been a passenger in one), it didnt seem to be as dramatic as would be starting and stopping a car without the function.
If it's like the Audi system, it does monitor the car's requirements and won't turn off if it's cold and/or there are system requirements, A/C on, seats etc., where turning it off could cause a problem!
I tend to turn the system off coz it's bloody annoying!!
However, my car being auto, to operate it u must leave yr foot on the brake, therefore dazzling drivers behind.....
I tend to turn the system off coz it's bloody annoying!!
However, my car being auto, to operate it u must leave yr foot on the brake, therefore dazzling drivers behind.....
mankey said:
melv said:
However, my car being auto, to operate it u must leave yr foot on the brake, therefore dazzling drivers behind.....
How about the handbrake? Mine's an automatic and contrary to loads of lazy drivers, I put the handbrake on when I come to a stop. Seems to make sense.Oh, I actually quite like it! But it did feel very strange at first.
On a 981 PDK it switches the engine off when you stop moving as long as you keep your foot on the brake.
That does at least relieve any doubts about wear on the PDK clutch (or whatever equivalent it has) while stationary, even though the manual says that's OK.
As soon as you take your foot off the brake the engine starts.
Applying the electric handbrake has no effect on the Stop Start as far as I can tell.
On a 981 PDK it switches the engine off when you stop moving as long as you keep your foot on the brake.
That does at least relieve any doubts about wear on the PDK clutch (or whatever equivalent it has) while stationary, even though the manual says that's OK.
As soon as you take your foot off the brake the engine starts.
Applying the electric handbrake has no effect on the Stop Start as far as I can tell.
Ady128 said:
Apparently it saves about 10% of fuel according to a Top Gear feature. I can't be bothered disabling it except in the rare occasions when I'm in heavy traffic. (991 PDK).
I can't see how it could save anything like 10%. For one thing many, if not most, drives it won't be operative for more than a few seconds or minutes, in possibly hours.Maybe on a particular drive, all in stop start traffic, you might get a considerable saving but overall, no way.
On the Cayenne it was intrusive to the point i'd turn it off regularly unless at a level crossing, long lights etc…, but it would shut the engine off at busy roundabouts, no matter how fast it starts I don't think that is good and same when turning right across traffic. Obviously it doesn't know the difference between pulling out a junction or roundabout to being in a queue of traffic.
I did think it should know you are turning right with some if indicator on don't shut off engine programming, though then I guess it won't turn off when turning right at traffic lights and they are red, so maybe it needs to be linked to a camera too so knows it it's a traffic lights……
On the other hand leave in sport mode and it's disabled
I did think it should know you are turning right with some if indicator on don't shut off engine programming, though then I guess it won't turn off when turning right at traffic lights and they are red, so maybe it needs to be linked to a camera too so knows it it's a traffic lights……
On the other hand leave in sport mode and it's disabled
I did find it annoying initially on my first Cayenne but after a while I kept forgetting to disable it and got used to it. Now I'm onto my 2nd Cayenne and its only during traffic where it moves a metre or two then stops that I switch it off. I just feel the extra stress on the starter motor and battery is greater in these circumstances.
Now I just blip the throttle at traffic lights etc to have the engine started prior to me needing to move, it doesn't seem to shut down after that for quite some time.
Don't see what the kerfuffle is about it.
Now I just blip the throttle at traffic lights etc to have the engine started prior to me needing to move, it doesn't seem to shut down after that for quite some time.
Don't see what the kerfuffle is about it.
REALIST123 said:
I can't see how it could save anything like 10%. For one thing many, if not most, drives it won't be operative for more than a few seconds or minutes, in possibly hours.
Maybe on a particular drive, all in stop start traffic, you might get a considerable saving but overall, no way.
IIRC 10% is a bit high/optimistic but if that's what TG found...Maybe on a particular drive, all in stop start traffic, you might get a considerable saving but overall, no way.
I will have to add having the benefit of examining considerable vehicle data from private vehicles and fleet vehicles most vehicles spend far longer idling than you would think.
In the case of my work commute, a 30 mile drive (one way), idle time can be 3 or more. This for a -- I just checked -- a drive in that took a bit over 31 minutes. (And this was a Sunday drive to the office. A week day commute: A 46+ minute drive time had the idle time almost 5 minutes. Same route. Traffic.)
Shorter trips, trips in town, can have the idle time approaching 1/2 the trip's elapsed time.
Have to point out fuel mileage with the vehicle stationary and the engine idling goes to pot.
On the 911 S we borrowed I sure it did it from cold can't remember about the brake but I do know at the time that I thought it was bad to sit on the brake blond cars behind.
I have a funny feeling that the manual Cayman we tried kept the engine off if you swapped to the stupid electric brake.
Seemed ok in economy mode but I can imagine it going horribly and expensively wrong in the future.
I have a funny feeling that the manual Cayman we tried kept the engine off if you swapped to the stupid electric brake.
Seemed ok in economy mode but I can imagine it going horribly and expensively wrong in the future.
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