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      12-07-2012, 04:28 PM   #10
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Drives: 2015, 740 LdX, Alpine White
Join Date: Mar 2011
Location: Boston Area

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Originally Posted by SomeRandomer123
As you will likely know, you're quite welcome to turn the engine off whilst in D with the automatic transmission, and it will revert to P itself.
And as some of you will know, if you leave the leaver in M/S (DS) it will also go back to P and move the stick itself!

But what is that actually moves the selector back to it's fully upright position? Have they installed a little electric motor purely for that purpose?

From an engineering standpoint, this is called a "stateless" system.

The main idea is that no matter what configuration, the the physical levers and buttons are not in any particular state such as "on," "off," "Drive," "Reverse," and so on.

The beauty of a stateless button, switch, or lever is that its function can be controlled via software as well as a human.

Another example is the volume control on the radio--on your BMW it is stateless. In other words it is not set to any particular volume level. In fact, it is impossible to tell if the volume is hi or low just by looking at the knob.

So, the beauty of the stateless system is that when you turn off your car while it is in drive, the computer can throw the car into park.

The turn signals levers are stateless too. Old analog cars would have a turn signal that would stay locked into the position you placed it into. However, the BMW stalk is stateless. Once you indicate where you want to turn, the stalk pops back to the neutral position. As such, at lease for me, the operation of the stateless turn signal stalk takes a while to get used to if you are familiar with the operation of older cars. My old 2005 750li didn't have this down...I can't tell you the number of times I would unintentionally indicate I was turning in the opposite direction of where I was going due to the goofy BMW design. The newer 750li and 5xx series do not have the problem.

Basically, when you went to turn off the turn signal, the detent was too soft and you could skip right past the neutral position and end up signing the opposite direction. BMW fixed this by making a much firmer middle detent.

Now, BMW had a conundrum. The shift gate that takes you to sport or manual would present a problem if it were not stateless. So, the system designers had to install a solenoid or similar device that can be controlled by the computer. Otherwise, the system would be in "park" while the shifter was in the manual/sport state.

So, technically, the shift gate isn't stateless. Why? Because you can tell that it is in manual/sport just by examination. However, the solenoid or other contraption emulates a stateless environment by moving the shift gate back to its normal position. No, it doesn't move the lever into park (since it is stateless) just moves the lever out of the sport/manual gate.

I find stateless systems to be fascinating. It is a really cool way of engineering because a stateless environment can be controlled remotely.

Finally, as of today, the steering wheel isn't stateless. But, someday it might be! Can you imagine what life would be like driving a car where there is no physical linkage between the steering wheel and the actual steering mechanism?