So...I took delivery of my Model 3 yesterday afternoon and the specialist indicated that "your phone is your key". This all worked wonderfully for about 24 hours after which my Tesla app wiped my car off the app and my online "My Tesla" account reverted back to the "Ready for Delivery" for my Model 3. I called Tesla and was told that the local delivery center can do a temporary override at delivery to ensure that everything works. This override goes away within 24 hours. The problem? It takes them 2 business day to do all the ownership transfers, etc. So...sure enough...at 24 hours, the override went away and my account went back to the old status because the ownership transfers hadn't been completed yet. What this means is that I couldn't use the phone to open the car. When talking to the Tesla person on the phone, he mentioned that you should always have the key card on you. This was not stated during my "delivery experience". So...be warned! ALWAYS carry your key card with you. Fortunately I had mine with me or I would have been stuck.