MSCHNEL

Hi All,
I'm new here but have been reading this forum for awhile and came across a post ( cant find it now) that I'd like to reply to. Some one stated that the most efficient MPG's were obtained using the DS mode and using wide throttle acceleration with at least 4,000 revs to get to cruising speeds. During this dicussion some one cited a BMW AG test indicating best mileage using heavy acceleration to obtain best mileage.

Well, that BMW corporate test actually stated that acceleration using high revs was actually counterproductive and that lowest fuel consuption was obtained with heavy throttle application in very high gears in a MANUAL GEAR BOX. In other words, using very low revs, shiting early and with higher thottle openings. Now, in my 550i, the DS mode essentially gives me a 5 speed auto box ( as it immeddiately goes from 6th gear to 5th gear when selecting DS from D ) and then extends the up-shift points under moderate to heavy throttle. Unless some of you have reversed the laws of thermodynamics, fluid physics, and common sense, I fail to see any logic in rapid acceleration, high revs if low fuel consumption is the issue! If fun is the end point, then I can understand. Also, to run around in DS in routine driving is to increase wear and tear on the engine and transmission. One other point: using manual mode and down shifting to slow the car in routine use ( as opposed to sport driving entering a curve and being in the right gear for the exit ) is certainly going to put a hell of a lot more stress on the gear box than using the brakes more vigorously. Brake pads are way cheaper than tranny rebuilds. Just my 15 cents!

znod

Welcome. Be sure and hang out; we have fun. Here is the thread you couldn't find. Have fun.

Bimmer32

What you say about the engine braking makes sense, but the problem is when I coast to the light or traffic, the engine brakes before I need to step on the brakes. So under such circumstances, should I not coast but rather brake to stop and limit the tranny from braking for me?

znod

If you were in DS, then you could hold 6th or whatever gear you are in and, thus, mostly brake to stop.

MSCHNEL

What you say about the engine braking makes sense, but the problem is when I coast to the light or traffic, the engine brakes before I need to step on the brakes. So under such circumstances, should I not coast but rather brake to stop and limit the tranny from braking for me?
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The shift sequence in the steptronic box will give some engine braking on deceleration which is normal. Braking with the actual foot brake is, ofcourse, used as necessary. What I meant was to decelerate on trailing throttle until foot braking becomes necessary rather than to manually downshift at higher road speeds which is an unnecessary burdan on the gear box. Higher oil consumption also accompanies trailing throttle-high RPM engine braking.

m630

....the car is meant to be driven, and driven agressively, so dont worry too much about oil consumption or burden on the gear box, thats what they are there for and that what the warranty is for...re-read the other thread and you should understand better on how the engine tranny work in the real world situations...i believe we are all speaking from experience so contrary to what you originally posted, there is no real efficiency lost by driving in DS, in fact it may help on the brakes in the long run if you trully drive the car as a clutchless manual,... i always use the engine to brake via the tranny, just as you would do in a traditionaly 6MT....plus i dont know anyone who actually would buy the 550i whos first concern was the most efficiency in gas consumption, of course its about the fun! when we speak about hi revs, in my case, that is the mid range, not the upper limits (5k+RPMs), so rapidly changing gears in the 3-4K range does produce acceptable fuel efficiency, as well as the most fun when not trully opening it up...

MSCHNEL

....the car is meant to be driven, and driven agressively, so dont worry too much about oil consumption or burden on the gear box, thats what they are there for and that what the warranty is for...re-read the other thread and you should understand better on how the engine tranny work in the real world situations...i believe we are all speaking from experience so contrary to what you originally posted, there is no real efficiency lost by driving in DS, in fact it may help on the brakes in the long run if you trully drive the car as a clutchless manual,... i always use the engine to brake via the tranny, just as you would do in a traditionaly 6MT....plus i dont know anyone who actually would buy the 550i whos first concern was the most efficiency in gas consumption, of course its about the fun! when we speak about hi revs, in my case, that is the mid range, not the upper limits (5k+RPMs), so rapidly changing gears in the 3-4K range does produce acceptable fuel efficiency, as well as the most fun when not trully opening it up...
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Specialist,

I was not implying that you could not, or should not drive as you wish. The original post on this subject had to do with fuel efficiency not fun or aggressive driving. There is NO WAY that using DS exclusively or using a high rev shift point is fuel efficient period! Many who post on these sorts of web sites do so to complain about their vehicals, often concerning such things as oil consumption, mileage, etc. My thread was to underscore a few simple facts.

m630

sorrry if it didnt come across well, but mostly i was speaking in jest. ...agreed that if a person uses DS and shifts each time at 6k+ , there will be no efficiency period....BUT, what I will say to you as I know you have just began to partake in our little community here is that unlike probably all other boards out there, usually here we are sharing good experiences and trying to help each other get the most out of our cars, not the usual bs of complaints you would see on most other boards...we do discuss problems of course, but we try to stay above the personal attacks at all costs and stick to the cars and driving experiences...you will see discussion revolving around fuel/oil/mileage etc, but we do accept that these are high end cars and when we talk about consumption we have to realize that we are driving top of the line cars with big v8s (in this case) so we have to laugh to ourselves to begin with when we start to talk about fuel efficiency...sure, there in no efficiency in driving a big v8 as compared to many other cars...but we already accept that, so the discussion revolved around comparable efficiencies in different drive/tranny settings and that is what was discussed originally in the other similar thread noted above...please feel welcome to comment and enjoy our community

Bimmer32

High end, low end, big engine, small engine, fun, not fun, fuel efficiency or not, we have the luxury to do all in the 5er v8. I'm glad for that. I think sometimes, we have too much spare time and begin to debate about theorectical things that we can't practically (or scientificallly) prove. So we go on debating for the sake of having fun debating a point we can't prove. Does that sound like politics?

MSCHNEL, welcome to the forum.