[checker]

Does this work when your phone runs out of charge, or do you need to find a good samaritan that will charge it for you?

[modeless]

The key card is your backup for when the phone isn't available for whatever reason. It's not a valet key, it's the main car key. (Valet mode is activated from the touchscreen, or your phone.)

Personally, I'm looking forward to not carrying a bulky fob with me everywhere. The key card will go in my wallet with my other cards, and my pockets will be lighter.