What I recently noticed at the red light

[booforty]

Interesting observations with the revs at the stop light. I'd be interested to hear the answer as to why the software does this.

[dosserj]

Originally Posted by bimmerj

As far as I know, most of the 2009 BMW, will have auto on/off. When you stop the car at a traffic light it will shutoff as long as your foot is on the brake, remove it and the car starts instantly. Like the hybrid.

I would not like this feature at all. I hope that is not standard in the States. How am I supposed to rev my engine to impress the girls in the car next when my car shuts off???

[mkoesel]

Originally Posted by bimmerj

As far as I know, most of the 2009 BMW, will have auto on/off. When you stop the car at a traffic light it will shutoff as long as your foot is on the brake, remove it and the car starts instantly. Like the hybrid.

How can this work in a sensible way? This type of system is fraught with disastrous side effects IMHO, and I am skeptical that it can be implemented reasonably as described. With a hybrid you have the electric motor to get you going quickly. No way the combustion engine can fire up as quick as I would need to if I had to get moving immediately to avoid being hit.

[J08M3]

Originally Posted by cchan

I think the answer might be simpler than that. If you are pressing down on the brake, the power assist for the brakes creates an extra load on the engine, causing the RPMs to dip slightly. Lifting off the brakes removes that load and the RPMs go back up. I've noticed something similarly on occasion on my other cars (never bothered figuring out exact conditions, maybe with AC on?), so it's probably not DCT or hill assist specific. Idle should be idle, but there's probably a certain tolerance range of RPMs, rather than a single exact RPM for idle.

I can assure you it's not the power assist for the brakes on a MT car. with foot on brakes and clutch depressed leave car in neutral, then move shifter into gear without lifting foot of brake or clutch and you will notice change in RPMs. I'm still pretty sure this is a software program to save on gas when you're not moving. I'm not sure if this is same with DCT cars. Has anyone else with MT noticed this?

[mkoesel]

Originally Posted by FifthStreetz

wow...you know ur not saving any gas turning the gas on and off right?? Its probably worse for the car to do that so often....

You know, I thought so too, but asme disagrees, at least with the first part:

http://sections.asme.org/florida/ASM...thbusters.html

as for wear and tear, well I suspect you are right on that (I suppose we could be wrong here too though). All that said, I personally never shut my car off unless I am exiting it.

[valeram]

From my ED experience last month, we were picked-up by Rolf (great service) and he was driving a diesel MT BMW. I noticed that the engine stop (0, zip RPM) when we hit a red light. I asked him about that and he said that it is a feature of the car. He just step on the clutch and off it goes as if that the car was running all along.

[m3larson]

Originally Posted by Big Windy

are you serious? turning your car off at a red light is not going to save you that much gas. your car does not consume that much gas at idle. turning it off is silly and just puts wear and tear on engine parts. an alternator is going to cost at least twice what you are going to save by shutting down at red lights. plus, if you were in front of me and had to start your car at a green, i'd be pissed!!

This was the big reason behind the push button start in the first place. Used in Europe for easy off and on at red lights.