Its a great Feature and also it gives different beeps depending where the key is !
Boot /In Car
You can lock the keys in the car, as I have done it !.
I put my jacket in the back, using the back door, shut the door, answered the mobile then heard a click as the doors locked......keys inside & me outside. Boot also locked, so spare keys were needed!.
Tried many times after, outside the house with the spare keys to hand & could recreate the problem using any passenger door. however, I couldn't manage to lock the keys inside the car by entering through the drivers door