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      11-01-2012, 11:12 AM   #10
JimD
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Drives: 128i convertible
Join Date: Apr 2009
Location: Lexington, SC

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I don't know how BMW does this but it is all programming. The car already has electronic controls for braking force for ABS and stability control. So the only added requirement is for logic. One way to design the logic would be to look for the car trying to go backward when it is in a forward gear and stop that. Judging just from how if feels, I don't think that is what BMW is doing. I think BMW is applying the brake after it is released possibly all the time but probably only when the angle of the vehicle says it is on a hill for a set period of time. That is pretty easy and helps. I think the vehicle angle sensors are also already there for stability control purposes.

I drive two manual transmissions regularly. I typically alternate daily. One is my bimmer with this feature and the other is a Suzuki SUV without hill hold. I like the extra margin of the hill hold but I've driven the SUV plenty enough to confidently start on a hill with somebody behind me. I rev the engine a little extra to avoid stalling but otherwise it is no big deal.

Jim
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128i Convertible, MT, Alpine White, Black Top, Taupe Leatherette, Walnut, Sport
Ordered 5/22/09, Completed 6/4/09, At Port 6/9/09, On the Georgia Highway 6/13/09, Ship Arrived Charleston 6/24/09 at 10pm, PCD 7/21/09
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