Keyless Entry?

[Lyons]

So, to unlock my car I can either use the remote or flick the handles up once (then a second time to open the door). And lock it by pressing hte button on the handle, or via the remote.

The build sheet of my car shows the advanced key/keyless option, but I just assumed it didnt have it as when I go near the car it doesnt unlock.

However, a couple of times in the last week before I have unlocked the car, it has unlocked by me simply standing beside it. From what I recall this has only happened at the drivers side front door.

Could battery life of the remote affect this? Or would it either work/not work just? Would it matter if the key was buried in a pocket below a jacket etc?

Just trying to get my head round why it doesnt work every time.