> My PaaK car has a backup passphrase to start it

Cars that need a physical cut key to go into a cylinder don't usually have backup passphrases.

No, but you can ziptie spares of said keys to an inconspicuous location on the vehicle -- just the valet key or the door key, depending on your tolerance for risk and whether or not the car came with them. (Credit to DeviantOllam for the idea.)

Cars should have pin pads to unlock them. They're so useful on my Fords.