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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > X Series > X3 F25 (2011 - current)

X3 F25 (2011 - current)
The latest X3 brings some added style and some new features to the BMW SUV family. Talk about the new F25 now!

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  #1  
Old 05-02-2014, 03:22 PM
Hockeymonkey Hockeymonkey is offline
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2015 X3 Coasting feature gas savings?

Looking at 2014 vs 2015 X3. Just curious as to why the 2015 X3 coasting feature makes zero difference in improved fuel economy when it comes to the EPA numbers?
I do 75% highway driving including some hills and thought this is really smart and should make the highway gas mileage much better than the 2014. I know the 2015s are just showing up but does anyone have a reason for why its not rated better? Maybe real world is better? I think the porsche cayenne had a similar coasting feature - again not sure if it made any real difference.
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  #2  
Old 05-02-2014, 04:37 PM
RhoXS RhoXS is offline
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In my opinion it is a bunch of crap - just a marketing thing. I am sure it does recover a finite amount of energy and that does translate to some finite saving in gasoline. However, I would bet, the amount saved is absolutely nothing consequential and worse, not justified by the cost of the equipment needed to implement this function or the resultant complexity that creates nothing but service issues.

It does take at least 7 Hp to run the alternator at its full 4KW capacity (.746 KW/HP + inefficiencies)and that is indeed consequential. However, I am sure the alternator does not begin to come close to averaging anything close to its full capacity and the system only does something useful when coasting down hill. Although BMW is indeed my favored manufacturer and I love all the BMWs I owned, I resent this feature as I think it adds unnecessary complexity for not a justifiable gain. Very poor engineering judgment in my opinion but probably great marketing judgment. Think about it - all the recovered energy is stored in a relatively small car battery that is already being maintained at 80% full charge so how much total energy is really recovered?

Last edited by RhoXS; 05-02-2014 at 04:38 PM.
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  #3  
Old 05-02-2014, 07:03 PM
todd92 todd92 is offline
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This isn't new for 2015.
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  #4  
Old 05-02-2014, 07:06 PM
poker838 poker838 is offline
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It's an alternator that runs on off throttle or on demand (if charge low). It's best not to confuse this as a hybrid style kinetic energy recovery system.
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  #5  
Old 05-02-2014, 07:27 PM
RhoXS RhoXS is offline
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Quote:
Originally Posted by poker838 View Post
It's an alternator that runs on off throttle or on demand (if charge low). It's best not to confuse this as a hybrid style kinetic energy recovery system.
Not sure what you mean but alternator is always mechanically connected just like any other vehicle, there is no clutch etc. Battery charging rate is controlled by modulating output voltage and this is done electrically, probably by controlling field voltage. The higher the output voltage and the more energy is driven into the battery. Just plug a voltmeter into the cigarette lighter socket in the center of the dash and you can see system voltage increase from 13.5 volts or so to 14.7 volts or so when the indicator below the tachometer indicates energy is being recovered. The intent of the system is indeed to recover kinetic energy but this recovered energy is used for battery charging only to minimize the alternators mechanical load on the engine. In a hybrid regenerative braking using the drive motor(s) recovers energy that is later used to propel the car.

Last edited by RhoXS; 05-02-2014 at 07:31 PM.
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  #6  
Old 05-03-2014, 10:00 AM
iHazaX3 iHazaX3 is offline
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As per Auto week regarding 2015 X3: "For efficiency, eco pro mode activates a coasting function that disengages the powertrain at speeds from 30-100 mph when the driver takes his foot off of the accelerator." I don't think I would want this feature, I don't even use the Auto Start/Stop feature since according to the owner's manual it can cause premature wear out of some ignition parts like the spark plug.

I have a 2014 X3 35i as my daily driver and I'm so happy with it's fuel economy. I'm getting better fuel economy than what's been published for a 35i. What I'm trying to say is even without the coasting feature, Auto Start/Stop and I'm not even using eco pro and I'm always in comfort mode, I'm already getting beyond 19/26 mpg, for me the fuel economy features are good to have but I can still get good mpg without using them.

Last edited by iHazaX3; 05-03-2014 at 10:02 AM.
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  #7  
Old 05-03-2014, 01:39 PM
Pilgrim Pilgrim is offline
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Quote:
Originally Posted by iHazaX3 View Post
As per Auto week regarding 2015 X3: "For efficiency, eco pro mode activates a coasting function that disengages the powertrain at speeds from 30-100 mph when the driver takes his foot off of the accelerator." I don't think I would want this feature, I don't even use the Auto Start/Stop feature since according to the owner's manual it can cause premature wear out of some ignition parts like the spark plug.
Absolutely! I WANT engine braking when I let my foot off the accelerator, and I want it any time I do that. I despise automatic transmission cars that don't engine brake in traffic - I constantly shift them down to get some engine braking.

I also completely agree on the start/stop. I have no desire at all to wear out my starter 5x as fast by having it kicking in all the time. Also, engine wear is most severe at startup when a pressurized oil film is not present on the bearings. This feature is bound to cause premature engine wear. In no way do I want a vehicle that has a start/stop function like that.

Can those functions be turned off? I'm thinking about an X3 with manual transmission next year, and if these would come with it I'll find a different car to look at.
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Last edited by Pilgrim; 05-03-2014 at 01:41 PM.
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  #8  
Old 05-03-2014, 08:24 PM
iHazaX3 iHazaX3 is offline
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@Pilgrim: With the 2014 once you turn off the Auto Start/Stop it will remain off unless you turn it back on again. The auto start/stop works really well with my Toyota Prius though because it's a hybrid and it doesn't have a huge engine to crank up. With the Prius, you can't even tell that the engine turned off and on. But with a performance car like a BMW, this feature will do more harm than good.

Last edited by iHazaX3; 05-03-2014 at 08:25 PM.
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  #9  
Old 05-04-2014, 05:18 AM
todd92 todd92 is offline
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Why will it do more harm than good? What difference does it make if it's a 'performance' car.
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  #10  
Old 05-04-2014, 07:23 AM
iHazaX3 iHazaX3 is offline
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Quote:
Originally Posted by todd92 View Post
Why will it do more harm than good? What difference does it make if it's a 'performance' car.
BMW puts a disclaimer on the auto start/stop function in the owner's manual. Mine is a 2014 and it's in page 63 under the sub header "The Concept". It states "Certain vehicle components may experience additional wear as a result of this system."

Anyway, in my opinion, I am not a car expert. Based on my own experience and observation with my Prius, the auto start/stop is well suited for my Prius because it has an electric motor that works hand in hand with the gasoline engine. Prius is engineered to switch seamlessly between electric and gas, I can't even tell if it's running in electric or gas because I can hardly feel and hear the engine, plus the big battery that can really power the car. My 35i is a different story, I can only cringe each time I hear the engine stops and starts and the way it shudders, I know that it is working really hard to bring back the engine to life. I guess the bottom line for me is I'm already getting 24-25 mpg 50% highway/50% city on somewhat hilly roads without using the auto start/stop and Ecopro, I cannot ask for more from a turbo charged I6. I bought my X3 for its enjoyable ride, my Prius saved me a lot of money but its ride is no way near to my X3.

Maybe on the next generations of X3, BMW will be able to perfect the auto start/stop technology until then I won't use this feature. It's just my own opinion.
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  #11  
Old 05-04-2014, 08:51 AM
RhoXS RhoXS is offline
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Quote:
Originally Posted by iHazaX3 View Post
BMW puts a disclaimer on the auto start/stop function in the owner's manual. Mine is a 2014 and it's in page 63 under the sub header "The Concept". It states "Certain vehicle components may experience additional wear as a result of this system."

Anyway, in my opinion, I am not a car expert. Based on my own experience and observation with my Prius, the auto start/stop is well suited for my Prius because it has an electric motor that works hand in hand with the gasoline engine. Prius is engineered to switch seamlessly between electric and gas, I can't even tell if it's running in electric or gas because I can hardly feel and hear the engine, plus the big battery that can really power the car. My 35i is a different story, I can only cringe each time I hear the engine stops and starts and the way it shudders, I know that it is working really hard to bring back the engine to life. I guess the bottom line for me is I'm already getting 24-25 mpg 50% highway/50% city on somewhat hilly roads without using the auto start/stop and Ecopro, I cannot ask for more from a turbo charged I6. I bought my X3 for its enjoyable ride, my Prius saved me a lot of money but its ride is no way near to my X3.

Maybe on the next generations of X3, BMW will be able to perfect the auto start/stop technology until then I won't use this feature. It's just my own opinion.

+1

Although I certainly want to maximize, within reason, economy, I do not purchase a vehicle with an emphasis on economy when I purchase a BMW. I just don't see the tiny gains in economy gained from ASS and the system that puts coasting energy into the battery to justify the additional cost, wear, complexity, and inevitable hit in reliability. In my opinion, these systems are driven by marketing forces and certainly not good engineering decisions.

My car does not have ASS but I had a new loaner with it when my car was being serviced a few months ago. I can absolutely 100% give assurance I would not tolerate this system for a nanosecond on any vehicle I owned.

Aside from the increased wear for a questionable gain in economy, I just did not like the engine stopping and then restarting. It was annoying and disconcerting. If this behavior was what I experienced over the past 60+ years then maybe it would be the norm to me now. However it is not and it again gets back to if I can afford to own a $50K BMW I am not going to tolerate inane and annoying economy features that do little or nothing.
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  #12  
Old 05-04-2014, 10:35 AM
Pilgrim Pilgrim is offline
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I don't have a problem with a start/stop on a Prius because I view it as a disposable car that will be useless after the battery pack wears out. If the engine and starter are tired by then, who cares? The car is done.

A BMW is a car I expect to run for much longer, and I don't want the extra wear of the start/stop process on the starter and the engine. I don't buy a BMW for fuel economy, I buy it for driving experience and performance.
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  #13  
Old 05-04-2014, 11:46 PM
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Eagle11 Eagle11 is offline
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Quote:
Originally Posted by Pilgrim View Post
I don't have a problem with a start/stop on a Prius because I view it as a disposable car that will be useless after the battery pack wears out. If the engine and starter are tired by then, who cares? The car is done.

A BMW is a car I expect to run for much longer, and I don't want the extra wear of the start/stop process on the starter and the engine. I don't buy a BMW for fuel economy, I buy it for driving experience and performance.
I second that, but have been blown away on the MPG I get with my 320i. I don't think the ASS makes that much of a difference and I know the Eco Pro doesn't help that much on the highway. I was driving between Phoenix and San Diego on a regular basis, once I drove it eco pro mode and got an extra 18 miles. I average 36 on highway with my 320.
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Old 05-15-2014, 05:42 PM
Hill Hill is offline
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Originally Posted by Pilgrim View Post
Absolutely! I WANT engine braking when I let my foot off the accelerator, and I want it any time I do that. I despise automatic transmission cars that don't engine brake in traffic - I constantly shift them down to get some engine braking.

I also completely agree on the start/stop. I have no desire at all to wear out my starter 5x as fast by having it kicking in all the time. Also, engine wear is most severe at startup when a pressurized oil film is not present on the bearings. This feature is bound to cause premature engine wear. In no way do I want a vehicle that has a start/stop function like that.

Can those functions be turned off? I'm thinking about an X3 with manual transmission next year, and if these would come with it I'll find a different car to look at.
I agree 100% about both start-stop and this 'coast' feature. I'd be strongly disinclined to buy a car that imposed those, whether I had the choice to use them or not.

But may I ask, pilgrim, what X3 with manual transmission you are considering? Unless I've done a very poor job of reviewing the features of the 2015 X3 models I haven't seen that any of them offer anything other than the 8-speed steptronic with manual mode. While manual mode is certainly a desirable function to have in an automatic transmission I don't think that it is what you mean when saying "with manual transmission" is it?
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Old 05-15-2014, 06:56 PM
Pilgrim Pilgrim is offline
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I agree 100% about both start-stop and this 'coast' feature. I'd be strongly disinclined to buy a car that imposed those, whether I had the choice to use them or not.

But may I ask, pilgrim, what X3 with manual transmission you are considering? Unless I've done a very poor job of reviewing the features of the 2015 X3 models I haven't seen that any of them offer anything other than the 8-speed steptronic with manual mode. While manual mode is certainly a desirable function to have in an automatic transmission I don't think that it is what you mean when saying "with manual transmission" is it?
I'm not interested in any X3 (or any other vehicle) with an automatic of any kind. Manual or nothing.

And I'm a used car buyer, so I'll happily go for something with 60-90K on it. There's no car in the world worth paying $40K or higher for me, so new BMW models aren't even a consideration.
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Last edited by Pilgrim; 05-15-2014 at 06:57 PM.
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  #16  
Old 05-15-2014, 07:18 PM
Want the Thrill Want the Thrill is offline
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Originally Posted by Pilgrim View Post
I'm not interested in any X3 (or any other vehicle) with an automatic of any kind. Manual or nothing.

And I'm a used car buyer, so I'll happily go for something with 60-90K on it. There's no car in the world worth paying $40K or higher for me, so new BMW models aren't even a consideration.
Then you will only be looking at X3's from 2004-2010. Very hard to come by.
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Old 05-15-2014, 10:03 PM
Pilgrim Pilgrim is offline
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Then you will only be looking at X3's from 2004-2010. Very hard to come by.
You're absolutely right! But they are out there, and that's the age range of car I will be looking for. I have no fear of well built cars that have miles on them. Many of the cars I have bought over the past 15 years have had 80K miles or more on them, and all have run to 160K miles without what I'd consider major problems that aren't routine for the mileage. If a 1999 Jeep Cherokee or 1991 Camaro can run to 165K miles without major problems, I don't think a BMW should have problems doing it.

That also leaves room for X5's and various Audis and Volvos with manual transmissions. I'm in it for the driving fun. That means I want a manual transmission car to behave like one - including having engine braking and not having the engine shut off at lights and wear out the starter firing up the engine so often. It's my gas and I'll be glad to pay for it.

HOWEVER - I now realize that I posted this in a 2011-up forum - and that's my error for not matching up the transmission options with the offering in the model year. My mistake!! Please excuse me.
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Last edited by Pilgrim; 05-15-2014 at 10:08 PM.
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  #18  
Old 05-16-2014, 08:42 AM
Hill Hill is offline
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Originally Posted by Pilgrim View Post
HOWEVER - I now realize that I posted this in a 2011-up forum - and that's my error for not matching up the transmission options with the offering in the model year. My mistake!! Please excuse me.
Ah. OK, no big deal. If you knew of some way of obtaining a new or very late model in the US with a manual transmission I'd be interested. I've never bought a car for myself with an auto trans and am nervous about the prospect. I spent a year at a bench rebuilding the things while in college and the possibility of complete failure at any moment (pump tang breaks off the torque converter is one way) is one I'd sooner live without.
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