I use an iPhone 6 with the Carly app and the only way to unlock the doors is not when I stop the engine, but when I pop the key from the ignition. It's like, turn off the engine and then tap the key and all doors will open. It makes sense if you stop to a gas station and you don't want to open all doors before making sure the surroundings are safe (I have kids), while you already turned off the engine.

There is an option to instantly pop the key when you turn off the engine, this way you'd have the car automatically open all doors using only the START/STOP button (called convenience-something, forgot the name) but there is no way, at least on my 2012 X35i, to have the doors open when i turn off the engine with the key still in the ignition. At least I haven't figure it out, yet. The downside is the car will shut everything off once the key pops out of the ignition. Most times I need to turn off the engine and still be able to listen to the radio.

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2012 X70 XDrive 35i