Coconut it's a bit confusing, assuming you are looking at getting a new 3 series the comfort access is only good if you have an automatic transmission.
You see the Manual you have to engage the clutch to start the car, thus the remote start is useless and in my mind a waste of money, $500!
It does work with the auto but who in there right mind would buy a BMW with an auto?
How the unlock works is you walk up to the car the doors unlock by touching the handle.
Via BMW...
Comfort Access system offers an even greater degree of convenience: keyless access to your car. Simply carrying the remote key in a pocket allows you to unlock the doors by touching the door handle. You can also turn the engine on or off by pressing the Start/Stop button* without first inserting the remote key.
*Foot must be on brake or, with manual transmission, must also depress the clutch in order to start.