Technical Car/Motor Issues > Ford Focus III - 13 1.6 Effect of Start-Stop Miscellaneous
Thread Author: L'escargot Replies: 16

 Ford Focus III - 13 1.6 Effect of Start-Stop - L'escargot
(a) What effect does Start-Stop have on fuel consumption? It's a pity that manufacturers don't quote official consumptions with the Start-Stop both enabled and disabled.

(b) What effect does having Start-Stop enabled have on the life of the starter motor and the flywheel gear ring? Does the cost of any saving in fuel really compensate for the increased wear on the starting system?
 Ford Focus III - 13 1.6 Effect of Start-Stop - Number_Cruncher
a) it depends how you use the car - in this regard, the divergence between the standard test cycles and realistic use will be marked.

b) starter motors are very robust, and I since pre-engaged starters have become a near universal fitment, I can't remember the last time I needed to fit a new ring gear.


As I've mentioned before, purely in terms of energy saving, it makes sense to stop the engine whenever it's idling for more than 10 seconds or so.
 Ford Focus III - 13 1.6 Effect of Start-Stop - Zero
>> (a) What effect does Start-Stop have on fuel consumption? It's a pity that manufacturers don't
>> quote official consumptions with the Start-Stop both enabled and disabled.


Given that you keep minutiae records with respect to fuel consumption, why dont you experiment with that and tell us what the effect is?
 Ford Focus III - 13 1.6 Effect of Start-Stop - VxFan
>> (a) What effect does Start-Stop have on fuel consumption?

5th gear did a test a little while ago. Can't remember the episode but you might find it on youtube.

Basically they either had two identical cars (except one didn't have SS technology) and they put the same amount of fuel in each and see how far they went on the same route and driving senario. Actually it might have been the same car but disabling the SS for one of the tests.

The one with SS went a bit further, btw.
 Ford Focus III - 13 1.6 Effect of Start-Stop - VxFan
>> might find it on youtube.

Here you go. Same car for both tests, btw.

www.youtube.com/watch?v=_nr0h7GXY6E

 Ford Focus III - 13 1.6 Effect of Start-Stop - L'escargot
>> www.youtube.com/watch?v=_nr0h7GXY6E

15% improvement in mpg isn't something I could get excited about.
 Ford Focus III - 13 1.6 Effect of Start-Stop - bathtub tom
>> 15% improvement in mpg isn't something I could get excited about.

I'd stop and fill up if I saw fuel 15% cheaper, that's around 20p/litre!
 Ford Focus III - 13 1.6 Effect of Start-Stop - Dave_
Cars with S/S have a meatier charging system, bigger battery and stronger starter motor. Virtually all the new cars we take out have it, from Polo BlueMotions up to Boxsters and X5s. Yes, its primary purpose is to combine with other efficiency and weight-saving measures to reduce the car's CO2 figure hence to put it in a lower BIK tax bracket, but it is handy for saving fuel in the real world too.

I've seen plenty of cars with 100k+ miles where everything including the s/s still works. I'd be happy to leave it on and not worry about it.
 Ford Focus III - 13 1.6 Effect of Start-Stop - L'escargot
>> Cars with S/S have a meatier charging system, bigger battery ........

Volvo deemed it necessary to fit two batteries on the V40.
 Ford Focus III - 13 1.6 Effect of Start-Stop - L'escargot
>> >> 15% improvement in mpg isn't something I could get excited about.
>>
>> I'd stop and fill up if I saw fuel 15% cheaper, that's around 20p/litre!
>>

I took Tiff Needell's word for it that the fuel consumption had increased from 58mpg to 67mpg, but when I did my own calculation based on the distances of 12.8 miles and 14.2 miles it transpires that it had only increased from 58.2mpg to 64.5mpg, i.e. 11% increase.
 Ford Focus III - 13 1.6 Effect of Start-Stop - Zero
Shocking, who only wants to save only 15p per litre of fuel.
 Ford Focus III - 13 1.6 Effect of Start-Stop - bathtub tom
>> it had only increased from 58.2mpg to 64.5mpg, i.e. 11% increase.

Hardly a fair test! New car, not yet run in, over less than 30 miles.

I'd think that if you could measure any sort of difference on that basis it's justified the stop/start.
 Ford Focus III - 13 1.6 Effect of Start-Stop - L'escargot
>> Hardly a fair test! New car, not yet run in, over less than 30 miles.

Exactly. And all of it around a city centre. What percentage of drivers only drive in city centres?
Last edited by: L'escargot on Fri 5 Apr 13 at 14:02
 Ford Focus III - 13 1.6 Effect of Start-Stop - VxFan
>> What percentage of drivers only drive in city centres?

Quite a lot, otherwise when quoting fuel consumption figures, they wouldn't bother giving urban figures.
 Ford Focus III - 13 1.6 Effect of Start-Stop - Zero


>> Exactly. And all of it around a city centre. What percentage of drivers only drive
>> in city centres?
>>


A much bigger percentage than those who live in the wilds of Lincolnshire.
 Ford Focus III - 13 1.6 Effect of Start-Stop - sooty123
>> A much bigger percentage than those who live in the wilds of Lincolnshire.
>>

Good job as well.
Last edited by: VxFan on Fri 5 Apr 13 at 16:54
 Ford Focus III - 13 1.6 Effect of Start-Stop - jc2
Me-never;if I'm in a city centre it's walk,bike or public transport.
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