The BMW app is not officially available
for the Samsung Gear S2 in our market or as far as I can tell anywhere outside of Germany. If I'm not mistaken, even that app is still a beta version. I've actually looked into it a while ago (purely out of boredom) and found very little on the, even on BMW's own blog (
http://bmwiforum.bmwusa.com/thread/565/iremote-on-galaxy-gear-s2). I must state that I have no experience with or interest in the Apple Watch and app (availability / compatibility / functionality) so I can't comment on that version.
The Gear S2 has just received a firmware update a couple of days ago and there is no mention of the BMW app or sign of it on the Gear's app store that I could find (I've just checked quickly). Even if it was available,
it only works with the i3 and i8 with no indication if it will ever be compatible with any other models in future. So unless you own an i3 or i8 or plan to in future, pursuing this or letting the availability / lack thereof of this app for the Gear S2 watch influence your decision to buy the watch or not is frankly pointless.
Keep in mind that the Gear S2 does not run standard Android or Android Wear, but Tizen which is Linux based.
You therefore cannot assume that because there is an Android phone app for something that there will be a Tizen version available. You will end up being bitterly disappointed in what the watch can/cannot do if you buy it without understanding this.
Locking and unlocking the car with the watch would be cool, but IMHO impractical for replacing the key fob for regular use. It is a party trick (IMHO of course), which will be used a couple of times until the novelty wears off. To the best of my knowledge, locking the car with the app also does not activate the alarm system, so it's a bit of a security risk compared to locking it with the key fob. It is only useful if the key has been lost or somehow locked inside the vehicle (not possible if the car has comfort access) and the car be be unlocked via the app or if the owner has forgotten to lock the vehicle and want to do so remotely (not near the car to use the key fob).
The car cannot be started without the key fob present.
The way the BMW Remote app on the phone works (not sure what your experience is with this, so my apologies if this is known information to you) is you:
1) open the app on the phone and enter the pass code (not required, but highly recommended)
2) go to the Remote tab
3) press and hold the desired action button (lock/unlock/headlight flash/etc.) for 2 seconds
4)the command is sent to BMW's secure servers/system
5)from there it is sent out to the vehicle
6)the vehicle "wakes up" and if all goes well, the command is executed
This action can take anything from several seconds to over a minute and is dependent on adequate cell service for both the device (phone/tablet) and the vehicle (with built in SIM and remote services option). I
assume that it would work the same with the watch. Even if it is simplified and added as a widget without some form of pass code (the watch can be set to lock automatically if removed from your wrist, which could be a replacement for the app/widget pass code), it would by no means be near as instantaneous as using the key fob. Keep in mind that the key fob is still required to start the vehicle, as stated above.
The only way that it would be a decent replacement for locking/unlocking via the watch is if it could use the Gear S2's integrated NFC instead, which would require BMW to add a NFC chip in the door handles or at least the driver's door handle. I doubt that they would go this route. Comfort access works just fine without any additional non-OEM hardware - phone/watch/??? - and is a much simpler and tried and tested alternative to using the buttons on the key fob.
My thoughts on the matter for what it's worth.
Feel free to ask any other questions regarding the Gear S2 (if you are interested in this particular smart watch) that you might be unclear on and I will attempt to answer to the best of my abilities, keeping in mind that I'm by no means an expert on it. Probably best to do so via PM as this is
way off of the forum's topic or general interest.