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Auto Start/Stop

5K views 24 replies 11 participants last post by  AzNMpower32 
#1 ·
I've noticed lately that when I come to a complete stop my car doesn't shut off as often as it used to when I first got the car. Even when the car is full with gas and the engine oil is at optimal temperature the car still doesn't shut off. I'm happy about this, but just wonder if its a result of a software update that BMW sent out or if it's because the temperatures have gotten colder........anybody else experience anything similar?
 
#3 ·
oh, ok...gotcha....
 
#4 ·
Half way through that thread, it was mentioned a couple of times.

http://www.bimmerfest.com/forums/showthread.php?t=585829

Funny you said you are rather happy about this.... This shows some general sentiment towards this feature.... Is it bugging you a lot and/or are your always conscious of it? Just wondering what ppl's opinion will be in a few months of usage.
 
#5 ·
it did bug me a lot because it was shut off as soon as i came to a complete stop....so if i pulled up to a stop sign, it would shut off which was very annoying....and it just feels like hte constant star/stop of the engine is adding more wear and tear to the car unnecessarily.....and i didn't find that the start/stop feature helped me save that much gas...
 
#9 ·
Too bad there isn't a button to disable "pulling to the right"...:tsk:
 
#11 · (Edited)
The Auto Stop-Start doesn't kick in when:

1. Outside temp <3°C or >30°C with switched on A/C.
2. Interior temperature not yet attained (i.e still heating up or cooling the cabin)
3. After driving in Reverse.
4. Battery is not fully charged
5. Engine not yet operationally warm.
6. Defrosting is in effect.
7. Stop & Go traffic
8. Engine bonnet/hood is unlatched.
9. HDC is activated
10. Large steering movement

Also, the driver can prevent the Stop-start function on a case-by-case basis. Immediately after the car is stopped but before the function cuts the engine, forcefully pulse/push the brake pedal to the floor then quickly release.

Do y'all read the owners manual?

I don't understand the fear of wear-and-tear on the engine. BMW has used this in MT cars in Europe since 2008. The starter and alternator are especially designed for this kind of operations. I do stop-start on my 2004 X3, and after 116.800 miles (188.000km) the starter still works fine. Considering I just replaced my first battery back in July, no real effect on battery life either.
 
#13 · (Edited)
I don't understand the fear of wear-and-tear on the engine. BMW has used this in MT cars in Europe since 2008. The starter and alternator are especially designed for this kind of operations. I do stop-start on my 2004 X3, and after 116.800 miles (188.000km) the starter still works fine. Considering I just replaced my first battery back in July, no real effect on battery life either.
Regardless, I for one think it will cause more wear and tear. I'm no engineer, but what about oil film on the cylinder walls every time the thing stops and restarts? Plus, air/fuel mixture is most likely enriched while starting. I can't imagine turning your engine off and on continuously is a good thing from a simple mechanical point of view. It's kind of like my wife turning off a light in the house knowing that I will be turning it back on in a minute (ie., bathroom). Bulb life is affected mostly by turn-on cycles, not constant burning. I think I'd be on the side of permanently disabling auto off/on if I owned a car with that "feature". Let someone else save the drop or two of gas.

The strict CAFE rules are now causing car manufacturers to resort to off the wall ideas. What's next, why not shut the engine off while cruising down a long incline -- no power is needed in that situation. H3ll, it restars in a matter of milliseconds, what's the big deal?
 
#14 · (Edited)
Auto start-stop has become pretty commonplace in Europe with most manufacturers, where CO² emissions and fuel consumption test cycles include a stopped period. North America is only starting to see the technology- automakers are probably doing it to streamline their worldwide manufacturing processes. Note that the EPA test cycle only started capturing more idling time with the 2008 revision, so incentive wasn't really there to add cost by adding Stop-start. No one complained about this when hybrids have it..........

As for coasting downhill, BMW already has that covered. With EfficientDynamics, the energy from coasting and braking is captured to charge the vehicle battery.

Seriously, what's wrong with saving fuel and the environment?
 
#15 ·
Here is my empirical take on Auto Start/Stop:

When I had my 2011 535 (exactly same engine and same car as my 2012) I was getting 21.5 MPG on my daily commute.

After getting the 2012 and leaving the Auto Start/Stop function enabled (default) I'm now getting 24.7 MPG constantly.

Same commute, same traffic. If anything, I should be getting worst mileage on the new car being it is barely broken-in. Instead, I'm getting more than 3 MPG.

3 MPG may not sound like much, but if you consider that I use an average of 20 gallons per week (refill every 6 days), I'm getting about 60 miles per week more.

Multiply the 60 miles extra per week x 52 weeks / year and you get 3,120 extra miles per year.

That is more than 6 weeks of free gas every year, or around $510 per year in gas.

Given that there is NO maintenance or warranty costs for 4 years, I will save over $2,000 in those 4 years, and I don't care if the car needs a new starter, as it will be covered by warranty. Also, most likely I will trade it in at the end of the 4 years.

So, bottom line, I like it, it saves money and it is good for the environment.

BTW, it should be fairly easy to change the switch from a NO (Normally Open) circuit to an NC (Normally Closed) type with a very simple in-line circuit.

How much would YOU be willing to pay for this circuit?
 
#16 ·
Here is my empirical take on Auto Start/Stop:

When I had my 2011 535 (exactly same engine and same car as my 2012) I was getting 21.5 MPG on my daily commute.

After getting the 2012 and leaving the Auto Start/Stop function enabled (default) I'm now getting 24.7 MPG constantly.

Same commute, same traffic. If anything, I should be getting worst mileage on the new car being it is barely broken-in. Instead, I'm getting more than 3 MPG.
That's interesting, and I agree that a consistent 3mpg difference is significant. I just wonder if there's any possibility that there is any other factor between your two cars other than the stop/start feature. It might be interesting to turn off stop/start for a full month or so and see if your mpg drops back to your 2011 F10 level. BTW, I drive 34 miles each way to work, I'd say about 1/2 in heavy stop-and-go traffic. I average 24mpg in my '11 535i.
 
#21 ·
Stop-start systems are only as good as the batteries that support them. Testing and on-the-road experience has shown that even the best AGM batteries lose their ability to support stop-start functionality after just one year [1]. While alternatives exist (NiZn, Lithium-Ion, Ultracapacitors, PbC), virtually all automakers continue to use conventional PbA (lead-acid) batteries proven inadequate for the task of stop-start.
[edit]

This may be the only real concern.
 
#22 ·
Yep, but one of the significant disadvantages to AGM's is that they don't take overcharging well. Enter BMW's efficient dynamics and only charging the battery some of the time and rarely charging it full.

Interesting that the thing that pisses some off (having to drive the car enough to keep it charged or make use of a trickle charger) is exactly the thing that may make start-stop work better.
 
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